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Publishing Alliance

2006 MRS Spring Meeting & Exhibit

April 17-21, 2006 | San Francisco
Meeting Chairs: J. Charles Barbour, Paul S. Drzaic, Gregg S. Higashi, Viola Vogel

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Symposium GG : Current and Future Trends of Functional Oxide Films

2006-04-18 Show All Abstracts

Symposium Organizers

Dhananjay Kumar North Carolina A&T State University

Valentin Craciun University of Florida

Marin Alexe Max-Planck Institute of Microstructure Physics

Kaushal K. Singh Applied Materials Inc.

GG1: Nanostructured Functional Oxide Films I

Session Chairs

Dhananjay Kumar

Tuesday PM, April 18, 2006

Room 2018 (Moscone West)

10:00 AM - **GG1.1

Multifunctional Complex Oxide Heterostructures

Ramamoorthy Ramesh ¹
¹, University of California, Berkeley, Berkeley, California, United States

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10:30 AM - GG1.2

Ferrimagnetic CoCr2O4 and NiFeO4 Nanopyramids by Self-Assembled Growth

Florencio Sanchez ¹, Nico Dix ¹, Ulrike Luders ², Jean Francois Bobo ², Josep Fontcuberta ¹
¹, ICMAB-CSIC, Bellaterra Spain, ², Onera, Toulouse France

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Nanoscale fabrication of multifunctional oxides can be done by self-assembled growth. It was demonstrated in multiferroic nanocomposites of ferrimagnetic spinel CoFe2O4 nanopillars embedded in a ferroelectric BaTiO3 matrix that were epitaxially grown. The nanostructured hybrid system showed coexistence of ferroelectricity and ferromagnetism, and displayed a remarkable coupling of magnetic and ferroelectric properties not observed in ordinary multilayer structures. Understanding the growth mechanisms of these nanocomposites is essential for its controlled fabrication and optimization of properties.The growth mechanisms of spinels have been much less investigated that those of perovskites. Here we report on the self-assembled growth of three-dimensional pyramidal objects in ferrimagnetic spinel, CoCr2O4 and NiFe2O4, epitaxial films. The spinel islands [2] have a shape very similar to the SiGe pyramids and hut clusters, but detailed characterization reveals important dissimilarities. They are {111} faceted pyramids and hut clusters, and thus have a very high aspect ratio, and moreover, they maintain the shape during growth. The objects are perfectly oriented along the <110> directions and have a certain positional order along the same direction. The growth progression was investigated: at early stages strained (dislocation free) small nanometric pyramids form, which is followed by a structural relaxation and a spectacular growth of some of the objects. We demonstrate that the size of the objects (from the nanometer to the micrometer) and area coverage (from isolated pyramids to fully faceted surfaces) can be controlled by the deposition time, growth temperature and substrate used. The driving forces for the observed {111} faceted objects and surfaces, and bi-modal or single-modal size distribution are discussed.Our demonstration of self-organized growth of ferrimagnetic spinel pyramids and hut clusters of controlled size and on different surfaces may open the possibility of controlled fabrication of hybrid systems combining these ferrimagnetic structures with other functional materials. References[1] H. Zheng et al., Science 303, 601 (2004); F. Zavaliche et al., Nano Letters 5, 1793 (2005)[2] U. Lüders et al., Phys. Rev. B, 70, 045403 (2004); Nanotechnology 16, S190 (2005)

10:45 AM - GG1.3

Self-selective Epitaxial Growth of BST Films: toward Nano-composite Structure for Microwave Tunable Devices.

Tomoaki Yamada ¹, Vladimir Sherman ¹, Andreas Noeth ¹, Paul Muralt ¹, Alexander Tagantsev ¹, Nava Setter ¹
¹Laboratoire de Ceramique, Ecole Polytechnique Federale de Lausanne, Lausanne Switzerland

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11:00 AM - GG1.4

Growth and Properties of a New Perovskite Thin Film – PbVO₃.

Lane Martin ¹, Qian Zhan ¹, Miaofang Chi ², Wenkan Jiang ¹, Rajesh Chopdekar ^{3 1}, Tong Zhao ^{1 4}, Nigel Browning ^{2 5}, Yuri Suzuki ^{1 6}, R. Ramesh ^{1 4 6}
¹Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, ²Chemical Engineering and Materials Science, University of California, Davis, Davis, California, United States, ³Applied and Engineering Physics, Cornell University, Cornell, New York, United States, ⁴Physics, University of California, Berkeley, Berkeley, California, United States, ⁵National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States, ⁶, Lawrence Berkeley National Laboratory, Berkeley, California, United States

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Over the past few decades, increasing attention has been given to investigating highly correlated electron systems, understanding the fundamental interactions between structure and properties in these systems, tailoring properties in such materials, and, recently, searching for new multiferroic materials. In this direction, vanadium-based perovskites have been widely studied and have been shown to exhibit interesting relationships between electronic properties and structure, are strong candidates for multiferroic behavior, and model systems for more fundamental studies of interactions between charge, orbital, lattice, and spin degrees of freedom. We report the growth of single phase, fully epitaxial thin films of a relatively new perovskite material, lead vanadate (PbVO₃) [1,2], using pulsed laser deposition. This growth realizes the first production of PbVO3 outside of high-temperature and high-pressure techniques through growth of epitaxial thin films on LaAlO₃ (001), (La_0.18Sr_0.82)(Al_0.59Ta_0.41)O₃ (001), and SrTiO₃ (001) substrates. Structural analysis of the PbVO₃ thin films using transmission electron microscopy, x-ray diffraction, and Rutherford backscattering spectroscopy reveals films that are single phase, highly crystalline, and have a tetragonally distorted perovskite structure similar to that reported previously, with a = 3.79Å and c = 5.02Å (c/a = 1.32). The large structural distortion arises due to the presence of the lone pair of electrons of the lead atom and results in a layered structure with vanadium in square pyramidal coordination. Previous studies of vanadium-based perovskites have found interesting connections between B-site valence and properties, specifically d² systems have shown Mott insulating behavior while d¹ system have shown metallic properties. Electron energy loss spectroscopy and x-ray absorption spectroscopy were used to show the stabilization of vanadium in the V⁴⁺ state, thereby proving the creation of a new d¹ system for intensive physical study. Additionally, the films exhibit semiconducting behavior in the plane of the film (ab-plane) with thermally activated behavior and distinctly different properties from other d¹ AVO₃ (A = Sr and Ca) thin films. Studies of the magnetism in PbVO₃ revealed weak ferromagnetism and slight differences between magnetism in the plane of the film and out-of-plane of the film and studies are underway to understand the cause of this behavior. [1] Shpanchenko, R.V., et.al., Chem. Mater. 16, 3267-3273 (2004).[2] Belik, A.A., et.al., Chem. Mater. 17, 269-273 (2005).

11:15 AM - GG1:Nano

BREAK

GG2: Nanostructured Multifunctional Oxide Films I

Session Chairs

Ramamoorthy Ramesh

Tuesday PM, April 18, 2006

Room 2018 (Moscone West)

11:30 AM - **GG2.1

Functional Oxide Films Based on Multicomponent Assembly of Nanocrystals.

Stephen O'Brien ¹, Christopher Murray ², Elena Shevchenko ^{1 2}, Dmitri Talapin ², Limin Huang ¹, Zhuoying Chen ¹
¹Applied Physics and Applied Mathematics, Columbia University, New York, New York, United States, ², IBM TJ Watson Research Center, Yorktown Heights, New York, United States

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12:00 PM - GG2.2

Low Field Magneto-transport Properties of (La_0.7Sr_0.3MnO₃)_0.5:(ZnO)_0.5 Nanocomposite Films.

Bo Soo Kang ¹, Haiyan Wang ¹, Yuan Li ¹, Quan Xi Jia ¹, Izabela Mihut ¹, Jonathan Betts ¹, Judith MacManus-Driscoll ^{2 1}
¹Materials Science & Technology, Los Alamos National Laboratory, Los Alamos, New Mexico, United States, ²Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom

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12:15 PM - GG2.3

Chemical Vapor Synthesis of Complex Nanocrystalline Oxides

Markus Winterer ¹, Vladimir Srdic ², Wei Jin ¹, Alexander Kompch ¹, Thomas Weirich ³
¹Department of Engineering, University of Duisburg-Essen, Duisburg, NRW, Germany, ²Department of Materials Engineering, University of Novi Sad, Novi Sad, Serbia, , ³Central Facility for Electron Microscopy, Rheinisch-Westfaelische Technische Hochschule (RWTH) Aachen, Aachen, NRW, Germany

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12:30 PM - GG2.4

Protective and Bio-compatible Nanostructured Surfaces by CVD Techniques: Controlled Modulation of Surface and Phase Structures

Sanjay Mathur ¹, Hao Shen ¹, Sven Barth ¹, Thomas Ruegamer ¹, Eva Hemmer ¹, Jessica Altmeyer ¹, Patrick Kuhn ¹, Christian Cavelius ¹
¹, Leibniz Institute of New Materials, Saarbruecken Germany

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Thin film deposition by CVD techniques plays a dominant role in the development of both protective and functional coatings, important for their technological implications. Commonly, multi-component materials are prepared from a mixture of precursors; however the efficiency of such processes is hampered by the mis-match of chemical reactivity among the precursors species. As a consequence, phase separation and elemental segregation is commonly observed in CVD deposited materials.The de-mixing of elements in multi-component systems is thermodynamically driven and sensitive to the chemical behaviour of the precursors. Transformation of precursor compounds possessing bonding features inherent to the solid-state lowers the need of diffusion and counterbalances the thermodynamic impediments. Recently, we have designed several new metal-organic systems and demonstrated their suitability to deposit corrosion-resistant and bio-compatible coatings on metallic and non-metallic substrates. For instance, different Mg-Al alkoxides, [MgAl2(OPri)8], [MgAl2(OBut)8] and [MgAl2(OBut)4H4] were used as molecular precursors to deposit MgAl2O4 spinel films. The growth parameters and the application potential of the MgAl2O4 deposits as corrosion-resistance was found to be governed by the intrinsic chemical configuration of the precursors that determine the microstructure and protective properties of the barrier coatings. A novel precursor, [FeIIFe2III(OBut)8], containing both Fe(II) and Fe(III) centres in the ratio necessary for the magnetite composition was developed for selective growth of epitaxial magnetite films. The preservation of valence and stoichiometry was effectively enforced by employing a molecular scaffold with appropriate Fe(II): Fe(III) stoichiometry (1:2) and preformed FeII–O(R)–FeIII units. Nanostructured iron oxide coatings were examined towards their cell compatibility. The experimental findings suggest that cell differentiation is positively influenced by the nano-topography and phase structure of the films.This talk will focus on the controlled modulation of surface composition (both structural and chemical) to achieve enhanced performance and combination of functional properties.

12:45 PM - GG2.5

Magneto-Optical Characterization of Multiferroic Thin Film Nanostructures

Matthew Corbo ¹, H. Zheng ¹, V. von Hinten ², E. Marinero ³, Y. Suzuki ¹, R. Ramesh ¹
¹Materials Science & Engineering, University of California, Berkeley, Berkeley, California, United States, ²Department of Technical Physics, University of Wurzburg, Wurzburg Germany, ³, Hitachi San Jose Research Laboratory, San Jose, California, United States

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GG3: Nanostructured Multifunctional Oxide Films II

Session Chairs

Stephen O'Brien

Tuesday PM, April 18, 2006

Room 2018 (Moscone West)

2:30 PM - **GG3.1

Novel Chemical Growth Routes of Functional Oxide Nanostructures and Epitaxial Films

Judith MacManus-Driscoll ¹, Ming Wei ¹, Ying Liu ¹, Ahmed Kursumovic ¹, Li Chao ¹, Mei Li ¹
¹Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom

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3:00 PM - GG3.2

Self-organized SiO2/Si Nanostructures Formed by the Competing Process of Thermal Oxidation and Etching.

Kun Xue ¹, Jian Xu ¹, Ho Ho ¹, Lei Wang ¹
¹Electronic Engineering department, The Chinese University of Hong Kong, Hong Kong Hong Kong

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3:15 PM - GG3.3

Ferromagnetic and Optic Properties of Transition Metal Doped Zinc oxide Nanoclusters above Room Temperature.

Jiji Antony ¹, David McCready ², Mark Engelhard ², Chongmin Wang ², Amit Sharma ¹, Joe Nutting ¹, Daniel Meyer ¹, Leah Bergman ¹, You Qiang ¹
¹Physics, University of Idaho, moscow, Idaho, United States, ²Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States

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3:30 PM - GG3.4

Novel Approach for Fabrication of Single Crystalline Insulator/Si/insulator Double Barrier Nanostructures Using Cooperative Vapour-solid-phase Epitaxy.

Dirk Kuehne ¹, Andreas Fissel ², Eberhard Bugiel ¹, H. Joerg Osten ^{1 2}
¹Institute of Electronic Materials and Devices, University of Hannover, Hannover Germany, ²Information Technology Laboratory, University of Hannover, Hannover Germany

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Quantum-effect devices based on silicon are promising for future nanoelectronic application due to their compatibility with mainstream technology. Here, double-barrier structures using epitaxial insulators as barriers and Si as quantum-well are particularly interesting. The fabrication of such an epitaxial insulator/Si/insulator heterostructure requires the growth of ultra-thin, atomically flat and defect-free insulator barriers on Si, and the growth of epitaxial Si quantum-well layers on the insulator. However, this can not be achieved straightforward because of the differences in the surface free energy between the insulator and silicon. Often, the surface free energy of the insulator is much lower than that of silicon leading to Si cluster formation on the insulator. This problem can be partly overcome using surfactants which suppresses island formation. However, the use of surfactants also introduces impurities into the epitaxial Si layer.We will present a new approach of nanostructure formation which is based on solid-phase epitaxy of the Si quantum-well combined with simultaneous vapour-phase epitaxy of the insulator on top of the quantum-well. In our experiments, we use the rare-earth oxide Gd2O3 as insulator, which has a large band gap of about 5.7 eV and a nearly equal valence-band and conduction-band offset, of 2.3 eV to Si respectively, as well as a low lattice mismatch of about 0.5 %. The structure consists of single crystalline Gd2O3/Si/Gd2O3 double barrier structure. It was grown on Si(111) by molecular beam epitaxy using electron beam evaporation of both silicon and granular stoichiometric Gd2O3. We will demonstrate that this new approach results in coherent and sharp interfaces between the underlying ultra-thin oxide layer and silicon as well as the ultra-thin silicon and the top oxide layer. The first Gd2O3 barrier was grown on Si at 670 °C. RHEED pattern obtained from the grown layer substantiates an epitaxial layer-by-layer growth in [111] orientation of the oxide layer. The oxide/Si(111) interface exhibits the known A/B twinning relationship where the B layer orientation is a twin related to the A substrate orientation obtained by a 180° rotation around the [111]-axis. Subsequent, an ultra-thin (2-4 nm) Si layer was deposited on top of the oxide under different conditions. Perfect double barrier structures were obtained as follows: Amorphous Si was deposited at low temperature. Then, the temperature was raised to 670 °C. During the temperature ramp-up, the deposition of the second oxide barrier was already started at medium temperature. This temperature was low enough to prevent the Si clustering. As revealed by RHEED, the second oxide barrier does not show significant differences compared to the first barrier layer. TEM investigation demonstrates that the Si quantum-well layer was also single-crystalline and contains only very few defects. The oxide/Si/oxide/Si(111) substrate interfaces were found to be atomically flat.

3:45 PM - GG3.5

Ga₂O₃ Nanoparticles Synthesized in a Low Pressure Flame Reactor.

Pascal Ifeacho ¹, Hartmut Wiggers ¹, Christof Schulz ¹
¹Institute for combustion and gas dynamics, University of Duisburg-Essen, Duisburg Germany

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Currently, strong research interest exists in fully understanding the potentials of 1-D gallium oxide nanomaterials such as nanowires, nanorods and nanobelts. Special emphasis is however placed on β-Ga₂O₃ with a monoclinic crystal structure for application as a transparent conducting oxide (TCO). Furthermore, it has been reported that β-Ga₂O₃ has huge potentials as an optical emitter for UV, as well as for high temperature gas sensors. However, most of the synthesis methods employed involves multi-step processes culminating with a thermal operation lasting several hours. While these processes are employed on laboratory scale and are essential for obtaining required objectives, they are often cumbersome for industrial applications. In this study, a one step approach for the synthesis and characterization of Ga₂O₃ is presented with particular emphasis on its optical properties for TCO applications. The synthesis of Ga₂O₃ was achieved by doping a H₂/O₂/Ar premixed flat flame with diluted trimethyl gallium Ga(CH₃)₃ in a low pressure reactor. Material properties such as mean particle diameter of the resulting metal oxide is characterized in-situ with a particle mass spectrometer (PMS) embedded in the low pressure reactor. It was observed that depending on the residence time for particle growth, mean particle diameters dp ranging between 2.5 nm ≤ d_p ≤ 6.5 nm are obtainable. This result was further collaborated by BET measurements, which yielded 200 m²/gm surface area, equivalent to a spherical diameter of 5 nm. XRD results show that the as-synthesized Ga₂O₃ nanoparticles are mostly amorphous, however, the observed broad reflexes can be ordered to the cubic crystal structure of Ga₂O₃. Consequently, by slightly reducing the overall oxygen concentration in the reactor, two new broad reflexes can be seen, indicating the presence of an additional phase. Using a pneumatic TEM sampling device, Ga₂O₃ nanoparticle were sampled on a TEM grid, whereby, image analysis indicated that the particles were agglomerated, but show spherical morphology. UV-VIS measurements show strong absorption in the UV range, which corresponds to the 4.8 eV direct band gap of bulk Ga₂O₃. The as-synthesized Ga₂O₃ nanoparticles were deposited on a silicon wafer for photoluminescence measurements. The deposited particles were excited with a 351 nm argon ion laser in vacuum, for excitation densities between 0.25 W/cm^-2 and 1500 W/cm^-2, as well as for temperatures between 4 K and 300 K. A broad emission band (blue light) ranging from 350 to 600 nm with a maximum at 460 nm was observed. The maximum corresponds to the 2.5 eV indirect band gap of Ga₂O₃, however, no significant shift in the photoluminescence spectrum was observed for increasing excitation density, but a slight red shift was observed at higher temperatures.

4:00 PM - GG3:Nano

BREAK

GG4: Nanostructured Multifunctional Oxide Films III

Session Chairs

Arunanva Gupta

Tuesday PM, April 18, 2006

Room 2018 (Moscone West)

4:30 PM - **GG4.1

Nanostructural Modification of High-Temperature Superconductors for Improved Properties.

David Christen ¹
¹, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

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5:00 PM - GG4.2

Growth Mechanisms and Magnetotransport Properties of SrRuO3 Thin Films

Gervasi Herranz ¹, Florencio Sanchez ¹, Josep Fontcuberta ¹, Maria Victoria Garcia-Cuenca ², Cesar Ferrater ², Manuel Varela ²
¹, ICMAB-CSIC, Bellaterra Spain, ²Fisica Aplicada i Optica, Universitat de Barcelona, Barcelona Spain

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5:15 PM - GG4.3

Solution Processing of High Quality Oxide Buffer Layers for Coated Conductor Fabrication.

Srivatsan Sathyamurthy ^{2 1}, Shafiq Bhuiyan ¹, Tolga Aytug ^{2 1}, Mariappan Paranthaman ¹
², University of Tennessee, Knoxville, Tennessee, United States, ¹, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

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One of the main focus areas of research in high-temperature superconductivity (HTS) in recent years has been on the development of the second generation wires also known as coated-conductors. One of the leading textured-template approaches for the fabrication of coated-conductors is the rolling assisted biaxially textured substrates (RABiTS) approach. In this approach, cube textured nickel or Ni alloy substrates, obtained by cold rolling and recrystallization, function as a template for the epitaxial deposition of buffer layers and the YBa2Cu3O7-x (YBCO) superconductor. The buffer layers provide a structural template for the HTS layer, and also act as a chemical barrier between the metal substrate and the HTS coating. Using such architecture, sufficient biaxial texturing of the HTS layer has been obtained to avoid problems associated with weak-linked, high-angle grain boundaries. To date, in the processing of high current coated conductors using RABiTS, the best reproducible results have been obtained using three layer buffer architectures such as CeO2/YSZ/Y2O3/NiW, where Y2O3 serves as a seed layer which nucleates a well textured oxide layer, YSZ is a barrier layer which prevents the diffusion of Ni into the superconductor, and CeO2 is a cap layer which promotes good epitaxy of the superconductor. This multi-layered buffer architecture is being successfully used in scale-up to long length, however, the manufacturing process could be simplified and potentially be lowered in cost if one could achieve a buffer stack with fewer components and utilize a scaleable, non-vacuum technique such as solution deposition. Using solution deposition we have developed thin films of a variety of novel pyrochlore oxides. In this study rare-earth zirconates and niobates were used. By careful process optimization, very highly oriented dense films of these oxides can be processed at very high rates. These films have a very fine grained microstructure with grain size of 20-30 nm. Using atomic force Microscopy the surface roughness of the films were estimated to be about 2-3 nm. Critical currents over 200 A/cm-width have been obtained on textured Ni-W substrates using La2Zr2O7 as the primary barrier layer. Through this study we have demonstrated that the performance of lanthanum zirconium oxide films processed by solution deposition is comparable to that of vacuum processed yttria stabilized zirconia. In this paper, the effect of film chemistry on diffusion barrier properties and crystallographic texture will be discussed._________________Research supported by the Department of Energy, Office of Electric Transmission and Distribution. This research was performed at the Oak Ridge National Laboratory, managed by UT-Battelle, LLC for the USDOE under contract DE-AC05-00OR22725.

5:30 PM - GG4.4

Studies on Nb Substituion at Cu site in YBa₂Cu₃O_7-x thin films.

Paul Barnes ¹, Srinivas Sathiraju ¹, G. Narasimharao ²
¹PRPG, Air Force Research Laboratory, Palm Coast, Florida, United States, ²Ceramics Division, Advanced Research Center for Powder metallurgy, Hyderabad, Andhra Pradesh, India

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5:45 PM - GG4.5

Mn2+ in ZnO thin films: Correlation Between Structural, Magnetic and Optical Properties.

Yves Dumont ¹, Ekaterine Chikoidze ¹, Hans Jurgen Von Bardeleben ², Jerome Gleize ³, Francois Jomard ¹, Edouard Rzepka ¹, Ouri Gorochov ¹
¹Laboratoire de Physique des Solides et Cristallogenese, CNRS-University of Versailles, Meudon France, ²Institut des Nanosciences de Paris, CNRS-Universities of Paris VI et VII, Paris France, ³Laboratoire de Physique des Milieux Denses, CNRS-University of Metz, Metz France

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2006-04-19 Show All Abstracts

Symposium Organizers

Dhananjay Kumar North Carolina A&T State University

Valentin Craciun University of Florida

Marin Alexe Max-Planck Institute of Microstructure Physics

Kaushal K. Singh Applied Materials Inc.

GG5: Spintronics I

Session Chairs

Hide Tanaka

Wednesday AM, April 19, 2006

Room 2018 (Moscone West)

9:15 AM - **GG5.1

Functional Oxide Films and Heterostructures.

Neil Mathur ¹
¹Materials Science, University of Cambridge, Cambridge United Kingdom

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9:45 AM - GG5.2

Magnetoresistance and Insulator-Metal Transition of EuO Thin Films Grown on YAlO₃ and Si Substrates.

Andreas Schmehl ¹, Venu Vaithyanathan ¹, Alexander Weber ², Jochen Mannhart ², Darrell Schlom ¹
¹Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, United States, ²Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg Germany

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With its impressive electronic, magnetic, and optical properties, the ferromagnetic semiconductor EuO is a fascinating compound for basic studies and for possible electronic applications. In Eu-rich EuO single crystals the ferromagnetic transition is accompanied by an insulator–metal transition with a resistivity drop of up to 13 orders of magnitude. Further, in single crystals the T_c as well as the magnitude of this transition can be shifted over a wide range by applying external magnetic fields. These dramatic property changes, together with the low charge carrier density and a reported spin polarization of about 100% in the ferromagnetic state, make EuO a very promising material for possible applications in spintronic devices, provided comparable properties can be achieved in thin films. To assess the properties of epitaxial EuO films, we grew Eu-rich EuO films by reactive molecular beam epitaxy (MBE) and characterized their structural, magnetic, and transport properties. The films were grown either directly on (001) Si using 12 Å thick SrO buffer layers or on (110) YAlO₃. As EuO is not stable in air the films were protected with capping layers of amorphous Al₂O₃. To make electric contact with the underlying EuO a novel process has been developed that combines in situ ion-milling and metal deposition. The structural properties were investigated using x-ray diffraction. For both substrate types these measurements indicate (001)-oriented, single-phase films, with [110] EuO being parallel to [110] YAlO₃ and [001] EuO being parallel to [001] Si respectively. Rocking curve widths, measured on the EuO 004 reflections, show values better than 0.4° FWHM for both substrate types. Four-point transport and SQUID measurements show ferromagnetic transitions with T_cs of about 75 K and a resistivity drops at the insulator–metal transition of about seven orders of magnitude. Application of external magnetic fields up to 8 T perpendicular to the film plane suppress the resistance near T_c up to five orders of magnitude and shift the transition temperatures to ≈150 K. These samples reveal the most pronounced magnetoresistive effect reported in EuO films.

10:00 AM - GG5.3

Phonon Modes, Dielectric Constants, and Exciton Mass Parameters in Ternary Mg_xZn_1-xO.

Carsten Bundesmann ¹, Ruediger Schmidt-Grund ¹, Daniel Spemann ¹, Michael Lorenz ¹, Marius Grundmann ¹, Mathias Schubert ²
¹Institut fuer Experimentelle Physik II, Uni Leipzig, Leipzig Germany, ²Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, United States

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10:15 AM - GG5.4

Room-temperature Ferromagnetic Zn_0.95Co_0.05O Diluted Magnetic Semiconducting Thin Films by Pulsed Laser Deposition.

Yuebin Zhang ¹, Qing Liu ¹, Thirumany Sritharan ¹, Sean Li ²
¹School of Materials Science and Engineering, Nanyang Technological University, Singapore Singapore, ²School of Materials Science and Engineering, The University of New South Wales, Sydney, New South Wales, Australia

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10:30 AM - GG5.5

Development of CMR Manganite Sensors for Energy Measurement of the Linear Coherent Light Source Pulsed X-ray Laser.

Rajeswari Kolagani ¹, Grace Yong ¹, Stephan Friedrich ², Yong Liang ³, David Cox ¹, Rajeh Mundle ¹, Owen Drury ², Zaheer Ali ², Vera Smolyaninova ¹, David Schaefer ¹, Anthony Davidson ¹
¹Department of Physics, Astronomy & Geosciences, Towson University, Towson, Maryland, United States, ²Advanced Detector Group, Lawrence Livermore National Laboratory, Livermore, California, United States, ³, Motorola Labs, Tempe, Arizona, United States

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We are developing CMR manganite thin films for use as bolometric sensors for energy measurements of the Linear Coherent Light Source (LCLS) pulsed free electron x-ray laser (FEL) which produces ultra bright x-ray pulses in the energy range between 0.8 keV and 8 keV with ~ 10 ¹² photons per pulse and pulse repetition rate of ~ 120 Hz. The sensor functionality is based on the steep temperature dependence of the resistance accompanying the insulator-metal transition in the CMR manganites. The sensor array is to be fabricated on a low Z (atomic number) substrate capable of withstanding the pulse impact of 2 mJ in ~ 200 femtoseconds, without the thermal expansion exceeding the yield strength, when the back side of the substrate is irradiated with the FEL pulses. Si is a potential candidate substrate that is expected to meet this requirement though its stability for long term exposure is a concern that needs to be experimentally tested. The optimal operating temperature of the sensor has been estimated to be in the range 100 K-200 K, based on finite element simulations of the temperature evolution in the sensor pixel. Our initial work has identified in Nd_1-xSr_xMnO₃ (NSMO) as the manganite material suitable for operation in this temperature range. We are developing thin films of NSMO on Si substrates by Pulsed Laser Deposition, employing several buffer and template layer schemes. We will present our materials development efforts towards meeting the LCLS sensor design and performance requirements. Effects of lattice mismatch and thermal strains on the structural properties as studied by 4-circle x-ray diffraction and the correlation of these with the electrical properties such as the insulator-metal transition and the temperature-coefficient of resistance will be discussed. We will also discuss our exploratory efforts on the growth of CMR manganite thin films on other potential low Z substrates such as BN which are intended to replace Silicon , in case Si proves to be unstable during long term exposure to the LCLS beam.

10:45 AM - GG5.6

Domain Formation in Nanoscale La_0.7Sr_0.3MnO₃ Islands Patterned By E-Beam Lithography and Ion Implantation

Yayoi Takamura ¹, Rajesh Chopdekar ^{1 2}, Yuri Suzuki ¹, Alexander Liddle ³, Bruce Harteneck ³, Andreas Scholl ⁴, Andrew Doran ⁴
¹Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, ²School of Applied and Engineering Physics, Cornell University, Ithaca, New York, United States, ³Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, United States, ⁴Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, United States

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The doped rare-earth manganite La_0.7Sr_0.3MnO₃ (LSMO) has received renewed interest in recent years due to its wide range of technologically relevant properties, including novel magnetic and electronic properties. These properties depend strongly on parameters such as strain, oxygen stoichiometry, doping, and the presence of grain boundaries. From a fundamental perspective and for the development of device applications, understanding the relationship between the magnetic properties and the size of LSMO structures is of great interest. Geometric confinement increases the surface area to volume ratio and alters the strain state in epitaxial thin films. Previously, Wu et al.¹ used optical lithography and ion milling to pattern pillars into LSMO thin films and used magnetic force microscopy (MFM) to image the domain patterns. The authors found that for pillars with diameters ≥ 500 nm, the magnetic properties are dominated by the compressive strain imposed from the LaAlO₃ substrate. For structures below a critical dimension, the competition between magnetostatic energy and exchange energy are predicted to suppress magnetic domain formation, leading to single domain structures. In this work, we use photoemission electron microscopy (PEEM) and MFM to probe the magnetism in submicron LSMO islands within a non-magnetic matrix patterned by a novel approach of e-beam lithography and ion implantation. The samples consist of 60 nm thick epitaxial thin films deposited on (001)- and (110)-oriented SrTiO₃ substrates by pulsed laser deposition. The choice of substrate orientation results in thin films with two- and four-fold in-plane anisotropy, respectively. A 500 nm thick resist pattern is used to define regions of varying shape and size that are/are not exposed to an Ar⁺ ion implantation at 100 keV with a dose of 1.0x10¹⁴ ions/cm². By disrupting the ordering of the lattice, the implanted ions cause the degradation of the magnetic and transport properties of the LSMO film. PEEM and MFM images reveal that the domain structure in the islands depends predominantly on the shape of the islands, with the magnetocrystalline and magnetoelastic energies contributing secondary effects. ¹ Y. Wu, Y. Matsushita, and Y. Suzuki, Phys. Rev. B 64, 220404 (2001).

11:00 AM - GG5:Spintronics

BREAK

GG6: Spintronics II

Session Chairs

Valentin Craciun

Wednesday PM, April 19, 2006

Room 2018 (Moscone West)

11:30 AM - **GG6.1

Highly Conductive (Fe,Mn)3O4 Thin Films with Spin Polarization at Room Temperature and Their Application to Nano Spintronic Devices by AFM Lithography

Tomoji Kawai ¹, Hide Tanaka ¹, Mizue Ishikawa ¹, Yoshihiko Yanagisawa ¹, Issei Satoh ¹, Hidekazu Tanaka ¹, Luca Pellegrino ^{1 2}
¹, ISIR, Osaka University , Ibaraki, Osaka, Japan, ², INFM-Lamia & Genova Universuty, Genova Italy

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12:00 PM - GG6.2

Epitaxial Ilmenite-Hematite Films by Pulsed Laser Ablation

J. Dou ^{1 2}, L. Navarrete ^{1 2}, P. Padmini ^{3 2}, P. Kale ^{3 2}, R.K. Pandey ^{3 2}, R. Schad ^{1 2}
¹Department of Physics , University of Alabama, Tuscaloosa, Alabama, United States, ²Center for Materials for Information Technology, University of Alabama, Tuscaloosa, Alabama, United States, ³Department of Electrical and Computer Engineering, University of Alabama, Tuscaloosa, Alabama, United States

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12:15 PM - GG6.3

A New Fundamental Limit of Ferroelectric Devices Set by Net Polarization Decay.

Jiyoung Jo ¹, D. J. Kim ¹, Y. S. Kim ¹, S. B. Choe ¹, T. K. Song ², J.-G. Yoon ³, J. S. Chung ⁴, T. W. Noh ¹
¹, Seoul National University, Seoul Korea (the Republic of), ², Changwon National University, Changwon Korea (the Republic of), ³, University of Suwon, Suwon Korea (the Republic of), ⁴, Sungsil University, Seoul Korea (the Republic of)

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12:30 PM - GG6.4

Femtosecond Pulsed Laser Deposition of Metal Oxide Thin Films

Bing Liu ¹, Arnold Alenic ², Zhendong Hu ¹, Yanbin Chen ², Yong Che ¹, Xiaoqing Pan ², Yuzuru Uehara ¹
¹, IMRA America Inc., Ann Arbor, Michigan, United States, ²Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States

Show Abstract

GG7: Ferroics and Device Applications

Session Chairs

Neil Mathur

Wednesday PM, April 19, 2006

Room 2018 (Moscone West)

2:30 PM - **GG7.1

Epitaxial Thin Films and Multilayers of Magnetocapactive and Multiferroic Double Perovskite Oxides

Arunava Gupta ¹
¹MINT Center, University of Alabama, Tuscaloosa, Alabama, United States

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Ordering of the B site cations in the double perovskite-type oxides, A2B’B’’O6, often results in novel electrical and magnetic properties due to the B’-O-B’’interaction. For example, a number of double perovskites are known that are either ferri- or ferromagnetically ordered with a magnetic Curie temperature (Tcm) close to or above room temperature, including A2FeMoO6 (A=Ba, Sr), A2CrWO6 (A = Ba, Sr), and La2NiMnO6. The latter (La2Ni2+Mn4+O6) is an ordered double perovskite that is a ferromagnetic semiconductor with a Tcm of 280 K. Recent studies of La2NiMnO6 in the bulk have revealed large magnetic-field induced changes in the resistivity and dielectric properties at temperatures close to Tcm [1]. This is a much higher temperature than previously observed for such a coupling between the magnetic, electric, and dielectric properties in a ferromagnetic semiconductor. Substitution at the A site can also lead to multiferroic behavior in the double perovskites. Azuma et al. have reported synthesizing the compound Bi2NiMnO6 in the bulk under high pressure (~ 6 GPa) and have established its multiferroic properties [2]. The presence of the 6s2 lone pairs of Bi3+ ions and the covalent Bi-O bonds results in ferroelectric properties with Tce of 485 K, while the -Ni2+-O-Mn4+-O-Ni2+- magnetic path leads to ferromagnetism with Tcm of 140 K. We have succeeded in growing high quality epitaxial films of both oxides on (100)-oriented SrTiO3 substrates using the technique of pulsed laser deposition (PLD). The magnetic and electric properties of the films are qualitatively similar to those observed in the bulk compounds, but with some differences resulting from the influence of strain. In addition, we have artificially layered these novel oxide thin films with other lattice-matched oxides and have been able to significantly alter their magnetocapactive and multiferroic properties. The details of the structure and property characterization of the single and multilayer films will be reported.1.N. S. Rogardo, J. Li, A. W. Sleight, and M. A. Subramanian, “Magnetocapacitance and magnetoresistance near room temperature in a ferromagnetic superconductor: La2NiMnO6”, Adv. Materials (in print).2.M. Azuma, K. Tanaka, T. Saito, S. Ishiwata, Y. Shimakawa, and M. Takano, “Designed ferromagnetic, ferroelectric Bi2NiMnO6”, J. Am. Chem. Soc. 127, 8889 (2005).

3:00 PM - GG7.2

Patterning of Hierarchical Multiferroic Oxide Nanostructures Using Soft Electron Beam Lithography (“Soft-eBL”).

Zixiao Pan ¹, Suresh Donthu ¹, Mohammed Aslam ¹, Vinayak Dravid ¹
¹Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States

Show Abstract

Material systems exhibiting simultaneous ferroelectric and magnetic ordering have drawn significant interest in recent years due to their remarkable potential in diverse applications such as memory elements, field sensors, transducers, among many others. Recent experimental results[1] have shown that nanostructured multiferroic oxide composites exhibit a strong coupling between ferroelectric and ferromagnetic order parameters. On the other hand, theoretical calculations[2] have further substantiated that the three-dimensional (3D) geometry of such composites and the heteroepitaxy between the two oxides constrained by the substrate ultimately determine its coupled functionality. Therefore there is considerable interest in development of new strategies to fabricate, and particularly, to pattern 3D hierarchically stacked multiferroic nanostructures in order to investigate the coupling interactions in such system where the size and site of each phase are well-controlled. In our group we have developed an innovative soft electron beam lithography (“soft-eBL”) approach[3] which combines the high resolution eBL with deposition of liquid precursors for patterning nanostructures of variety of hard, soft and hybrid materials. We have further demonstrated that the soft-eBL approach can be utilized for patterning of radially stacked hierarchical structures composed of ferroelectric and magnetic ceramics in a facile two-step procedure[4]. For example, well-defined nanorings of lead zirconium titanate (PZT) are first fabricated on variety of substrates. The nanorings are then used as building block “containers” and filled with CoFe2O4 (CFO) to form radially stacked composite ceramic heterostructures. This approach circumvents the traditional bottlenecks of painstaking feature-realignment and etching for patterning of non-planar, multi-phase oxide structures. Such hierarchical PZT/CFO radial composites may serve as an interesting test bed to study the coupling effect by controlling the geometry and the microstructure of each phase.The presentation will cover the soft-eBL strategy for nanopatterning of functional inorganics, particularly to demonstrate the efficacy of this novel approach in fabricating hierarchical multiferroic oxide nanostructures, and emphasize the need to couple nanopatterning with control over microstructure and assessment of functionality of such structures.[1] Zheng, H. et al., Science 303, 661 (2004)[2] Liu, G. et al., J. Phys. D: Appl. Phys. 38, 2321 (2005)[3] Donthu, S. et al., Nano Lett., 5, 1710 (2005)[4] Pan, Z. et al., Small, accepted

3:15 PM - GG7.3

Electric Field-induced Magnetization Reversal in BiFeO₃-CoFe₂O₄ Multiferroic Films.

Florin Zavaliche ^{1 2}, H. Zheng ^{1 2}, T. Zhao ^{1 2}, L. Mohaddes-Ardabili ¹, S. Y. Yang ¹, Q. Zhan ^{1 2}, M. P. Cruz ^{1 2 3}, P. Shafer ¹, D. Hao ¹, J. Zhang ⁴, M. L. Scullin ¹, D. G. Schlom ⁴, L. Q. Chen ⁴, R. Ramesh ^{1 2}
¹Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, ²Physics, University of California, Berkeley, Berkeley, California, United States, ³, Centro de Ciencias de la Materia Condensada (CCMC)-UNAM, Ensenada, B.C., Mexico, ⁴Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, United States

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3:30 PM - GG7.4

Enhanced Electrical Properties of Hf-O-N Gate Dielectric Thin Films.

Karthik Ramani ¹, C.R. Essary ¹, V. Craciun ¹, R. K. Singh ¹
¹Materials Science and Engineering, University of Florida, Gainesville, Florida, United States

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3:45 PM - GG7.5

Potential Distribution and Domain Structure of Metal-ferroelectric-semiconductor-metal Heterostructures.

Rene Meyer ^{1 2}, Paul McIntyre ²
¹Materials Sciences and Engineering, Stanford University, Stanford, California, United States, ²CNI, FZ Juelich, Juelich Germany

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4:00 PM - GG7: Ferroics

BREAK

GG8: New Dielectrics

Session Chairs

Leonard Uitenham

Wednesday PM, April 19, 2006

Room 2018 (Moscone West)

4:15 PM - **GG8.1

Lattice Matched Dielectrics for Widebandgap Semiconductors.

B. Gila ¹, M. Hlad ¹, D. Stodilka ¹, S. Jang ², K. Allums ¹, A. Herrero ¹, A. Onstine ¹, J. Chen ², F. Ren ², Cammy Abernathy ¹
¹Department of Materials Science and Engineering, University of Florida, Gainesville, Florida, United States, ²Department of Chemical Engineering, University of Florida, Gainesville, Florida, United States

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4:45 PM - **GG8.2

Functional Oxides Grown by Molecular Beam Epitaxy.

Jean-Pierre Locquet ¹, A. Guiller ¹, C. Marchiori ¹, M. Sousa ¹, A. Ruefenacht ², B. Mereu ¹, D. Caimi ¹, H. Siegwart ¹, D. J. Webb ¹, R. Germann ¹, P. Martinoli ², C. Rossel ¹, J. W. Seo ^{3 4}, C. Dieker ⁴
¹, IBM Research GmbH, Rueschlikon Switzerland, ², Universty of Neuchatel, Neuchatel Switzerland, ³, MosBeam Foundation, Lausanne Switzerland, ⁴, EPFL, Lausanne Switzerland

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5:15 PM - GG8.3

Metal-Organic-Chemical-Vapor Deposition of Amorphous Thin Sr-Ta-O and Bi-Ta-O Films for Incorporation in Backend Integration of High-k Capacitors.

Ludovic Goux ¹, Hans Vander Meeren ¹, Dirk Wouters ¹
¹SPDT, IMEC, Leuven Belgium

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Dielectric layers with high dielectric constant, low leakage and high breakdown strength are of great interest for application in devices like Dynamic RAM, decoupling capacitors, or impedance matching capacitors. In particular, the need for high capacitances integrated on chip in the back-end-of-line interconnect is increasing. For these applications, process temperatures should be <400°C if Cu/low k interconnects are used.In this work, we prepared Pt/Sr-Ta-O/Pt and Pt/Bi-Ta-O/Pt capacitors on silicon, where dielectrics were deposited as amorphous layers at 360°C by metal organic chemical vapor deposition (MOCVD). All the films were dense and smooth. The thickness (t) of the dielectrics ranged between 5 and 100 nm. Both X-ray fluorescence (XRF) and scanning electron microscopy (SEM) were used to monitor the thickness of the dielectrics, while XRF gave access to their composition. After capacitor fabrication, current-voltage (I-V) was carried out using a conventional parameter analyzer, while capacitance and loss measurements (tgd) were made using a LRC analyzer.The effect of the temperature of the recovery anneal applied after Pt top electrode deposition was studied. For Bi-Ta-O (BT) -based capacitors, a 10min. long anneal at 300°C was sufficient to cure the plasma damage, while higher anneal temperature led to the increase of the leakage. For Sr-Ta-O (ST), leakage was minimized for annealing at 500°C.For both materials, the capacitance was well above 2 μF/cm2 for t ≤ 10 nm. Extrapolation to t = 0 indicated absence of a low-k interface layer. The extracted dielectric constant ε was 20 for ST, and 50 for BT. For both capacitors the capacitance did not vary from –3 to 3 V and tgd was kept within reasonable limits up to 1 MHz for t ≥ 20 nm.Leakage level around 2.10-8 A/cm2 at 3 V was achieved for 20 nm thin ST, that is at least 1 decade lower than reported for atomic layer deposited Sr-Ta-O. For 20 nm thin BT, leakage was ~3.10-8 A/cm2 at 3 V. For both ST and BT dielectrics, leakage levels were lower than typically reported for other dielectrics investigated for same applications.The breakdown voltage scaled with the thickness, and the extracted breakdown field was ~6 MV/cm for ST and ~3 MV/cm for BT.These results show that both types of dielectrics Sr-Ta-O and Bi-Ta-O are promising for incorporation in backend integrated high-k capacitors. Particularly, their leakage level is lower than reported for other dielectrics, which constitutes a significant advantage for memory application. The results also suggest that MOCVD is a suited technique to obtain very thin Sr-Ta-O and Bi-Ta-O films which are dense, smooth and with good interfacial quality.

5:30 PM - GG8.4

Characteristics of Lateral Capacitor Based High-K Materials

Thottam Kalkur ¹
¹Dept. of ECE, University of Colorado, Colorado Springs, Colorado, United States

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5:45 PM - GG8.5

Reactive Deposition of Metal Oxide Films from Supercritical Carbon Dioxide.

Adam O'Neil ¹, James Watkins ¹
¹Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts, United States

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Recently we reported that the deposition of device quality metal films within high aspect ratio features is enabled by supercritical fluid deposition (SFD). Here we discuss extensions of this technique to high purity, conformal metal oxide films, including cerium and hafnium oxides, using a novel approach that involves the hydrogen-assisted reduction of metal precursors and subsequent spontaneous oxidation to yield the target material. The films are prepared in a cold-wall pressure vessel using supercritical carbon dioxide as solvent.Supercritical fluids (SCFs) provide a means to conduct solution-based processes in a medium that behaves much like a gas. By comparison to liquids, SCFs offer lower viscosities, higher diffusivities, miscibility with gas phase reagents and the elimination of surface tension. Moreover, many organic and organometallic compounds, including a number of CVD precursors, are soluble in CO₂ or other SCFs. This is an important advantage for reactive depositions because it eliminates precursor volatility constraints and can yield precursor concentrations several orders of magnitude greater than those realized during CVD deposition. H₂-assisted SFD has been used to deposit conformal Cu, Co, Ru, Ni, Pt, Au metals in high aspect ratio features. Detailed kinetic studies demonstrate that conformal deposition for Cu facilitated by reaction-rate-limited film growth that is zero order in precursor at the elevated precursor concentrations accessible in SCFs. The SFD technique has now been adapted for the deposition of metal oxides including cerium and hafnium oxides. Films were deposited by the H₂-assisted reduction of tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato) cerium and hafnium precursors. Spontaneous oxidation of the incipient films yields the target materials. Depositions were conducted on silicon test wafers in the presence of hydrogen and trace amounts of water at 200 - 300 °C, for cerium oxide and 250 - 350 °C, for hafnium oxide. No additional oxygen source was necessary. Planar films between 80 and 300 nm thick for cerium oxide and 40 and 90 nm thick for hafnium oxide were deposited and exhibited excellent adhesion to the substrate wafers. XPS analysis shows cerium oxide was deposited as a mixture to the cerous(III) and ceric(IV) forms, while hafnia was deposited solely as HfO₂. Annealing at 600 °C reduced the mixed cerium oxide films to pure cerous oxide, while the hafnia films were unchanged. All films were free of carbon contamination within the detection limitations of our XPS instrument. SEM analysis indicated that conformal coverage and filling of via structures is readily accessible using SFD. AFM analysis revealed as-deposited RMS roughness of 3.1 nm for cerium oxide and 1.25 nm for hafnium oxide.

GG9: Poster Session: Multifunctinal Oxide films and Devices

Session Chairs

Dhananjay Kumar

Thursday AM, April 20, 2006

Salons 8-15 (Marriott)

9:00 PM - GG9.1

Tuning Self-assembled Perovskite-spinel Nanostructures.

Haimei Zheng ¹, Qian Zhan ¹, Florin Zavaliche ¹, Matt Sherburne ¹, Florian Straub ¹, M. Cruz ¹, Long-Qing Chen ², Uli Dahmen ³, R. Ramesh ¹
¹Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, ²Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania, United States, ³National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States

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9:00 PM - GG9.10

Vanadium Adsorption and Vanadium Oxide Formation on Hematite(0001).

Donald Ellis ^{1 2}, Jianjian Jin ¹, C-Y Kim ³, Xiaoyan Ma ^{4 2}, A. Escuadro ³, Michael Bedzyk ^{3 1 2}
¹Physics and Astronomy, Northwestern University, Evanston, Illinois, United States, ²Institute of Environmental Catalysis, Northwestern University, Evanston, Illinois, United States, ³Mat. Sci. Eng., Northwestern University, Evanston, Illinois, United States, ⁴Chemistry, Northwestern University, Evanston, Illinois, United States

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9:00 PM - GG9.11

Chemical Vapor Deposition of Titanium-doped Vanadium Oxide Thin Films for Bolometer Application.

Shan-Wei Fan ¹, Wei-Chang Yang Yang ¹, Tai-Bor Wu ¹
¹ Materials Science and Engineering, National Tsing-Hua University, Hsin-Chu Taiwan

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9:00 PM - GG9.12

Low Resistance Ohmic Contact to p-ZnO Using Pt/Ni/Au.

Ji-Myon Lee ¹, Kyoung-Kook Kim ², Hitoshi Tampo ², Akimasa Yamada ², Shigeru Niki ²
¹Materials Science and Metallurgical Engineering, Sunchon National University, Chonnam Korea (the Republic of), ²Thin Film Compound Semiconductor Team, Institute of Advanced Industrial Science and Technology(AIST), Tsukuba Japan

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9:00 PM - GG9.13

Comparative Analysis of VO2 Thin Films Prepared on Sapphire and SiO2/Si Substrates by the Sol-gel Process.

Byung Gyu Chae ¹, Hyun-Tak Kim ¹, Sun-Jin Yun ¹, Bong-Jun Kim ¹, Yong-Wook Lee ¹, Kwang-Yong Kang ¹
¹, ETRI, Daejeon Korea (the Republic of)

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9:00 PM - GG9.14

Development of Devices based on a-InGaO3(ZnO)x filmsDeposited by Pulsed Laser Deposition

Arun Suresh ¹, Anuj Dhawan ¹, Praveen Gollakota ¹, John Muth ¹
¹Electrical and computer engineering, NC State University, Raleigh, North Carolina, United States

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9:00 PM - GG9.15

Vapor-Phase Functionalization of Nanostructured Gradient-Index Titanium Dioxide Thin Films

Andy van Popta ¹, John Steele ¹, Shufen Tsoi ¹, Enrico Fok ², Jonathan Veinot ², Michael Brett ¹, Jeremy Sit ¹
¹Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada, ²Chemistry, University of Alberta, Edmonton, Alberta, Canada

Show Abstract

Chemical treatments, when applied to nanostructured oxide thin films, can be used to generate added functionality for devices. In this study, nanostructured thin films were prepared by glancing angle deposition (GLAD) of rutile titanium dioxide, and functionalized with a monolayer of 3,3,3-trifluoropropyl-trichlorosilane to render the films insensitive to variable humidity conditions.GLAD is a form of physical vapor deposition that combines in situ substrate motion with low adatom mobility to create engineered thin-film nanostructures with high porosity. In the past, GLAD has successfully been applied to both inorganic and organic compounds to create columnar thin films composed of helices, chevrons, vertical posts, and various heterostructures. We will present experimental results detailing how GLAD was used to fabricate a defect-mode rugate filter through careful manipulation of the substrate tilt angle. At large tilt angles, the effective refractive index is low because the thin-film layer is primarily composed of air-filled pores. At small substrate tilt angles, the effective refractive index is high because the thin-film layer is very dense. By oscillating the deposition angle between 30° and 80°, the desired sinusoidal refractive-index profile can be created. A defect-mode, in the form of a narrow-bandpass, was added to the filter by integrating a π phase-shift into the index profile of the film. Like many porous optical materials, the gradient-index TiO₂ filter is sensitive to humid environments. At high humidity levels, water adsorption within the thin-film pores causes the effective refractive index to increase, producing a large red-shift in the optical transmission spectrum. The defect-mode experiences a 40 nm wavelength-shift as the relative humidity is increased from 0% to 90%. In order to stabilize the optical properties, the porous films were placed in an oxygen plasma reactive ion etch to saturate the TiO₂ surface in hydroxyl groups, and then functionalized with 3,3,3-trifluoropropyl-trichlorosilane (TFP-SiCl₃). Application of TFP-SiCl₃ reduces the shift in the defect-mode wavelength by more than six times over a large range of humidity levels. Aqueous contact angle measurements show that the originally hydrophilic TiO₂ films become hydrophobic when functionalized (films exhibit advancing contact angles as large as 118°), and capacitance measurements are used to confirm these results. The goal of applying a siloxane-based chemistry is to eliminate sensitivity to water vapor; however, the basic techniques involved can easily be adapted to alternative chemical reagents in order to create functionalized optical devices for use in a variety of gas sensors and nano-biosensors.

9:00 PM - GG9.17

Microwave Properties of Magnetron Sputtered Ba_0.5Sr_0.5TiO₃ Thin Films on (0001) Sapphire Substrates

Ernest Fardin ¹, Anthony Holland ¹, Geoffrey Reeves ¹, Patrick Reichart ²
¹School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia, ²School of Physics, University of Melbourne, Melbourne, Victoria, Australia

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9:00 PM - GG9.18

Structuring of Low Firing Temperature PZT Thick Films by Photolithography.

Stefan Schimpf ¹, Erik Ansorge ¹, Bertram Schmidt ¹
¹IMOS, Otto-von-Guericke-University , Magdeburg, Sachsen-Anhalt, Germany

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SummaryStructured piezoelectric PZT thick films were fabricated on silicon wafers. Different supplements, like lead oxide and different glasses, were added to the PZT to enhance the sintering. The films were structured by doctor blading on an epoxy based photoresist (SU8) mask. This allows very accurate micro patterns of high quality piezoelectric material. A multi-step firing process was developed to gain PZT structures more than 100µm thick and smaller than 100µm in lateral size. The structures were electrically contacted, poled and characterized.MotivationPZT (Lead Zirconate Titanate) is a cost-efficient and readily available piezoelectric material. Generally it is used by sintering powder into macro-sized electroceramics. Micro-Electro-Mechanical Systems often require forces or torques that could be generated by microstructured PZT films. This is a simple, flexible and low-cost way to drive MEMS. Conventional PZT thick films are produced by screen printing PZT with a lead oxide supplement [1]. These films are virtually impossible to be produced and aligned in microscale, since the screen printing process is very inaccurate. They have to be fired at temperatures of about 900°C-1000°C. This leads to a degradation of the platinum electrodes [2] and will prevent the use of any temperature sensitive structures along with the PZT. Additionally the lead oxide tends to leak out of the PZT structure. Apart from being poisonous and harmful to the environment this lead oxide can interfere with other structures on the substrate.ResultsThe epoxy based photoresist SU8 was used as a mask for printing PZT paste. The accuracy of the fabricated structures was limited by the photolithography and the grain size in the paste only. Test patterns were designed and the limitations of possible geometries were investigated. Different glasses were used as supplements to promote the sintering at reduced firing temperatures. The results were compared to conventional lead oxide containing PZT films in terms of mechanical stability and electromechanical behavior. Since the glasses have different softening points different firing profiles were used and compared. References[1] Ferrari V., Marioli D., Taroni A., Ranucci E., Multisensor array of mass microbalances for chemical detection based on resonant piezo-layers of screen-printed PZT, Sensors and Actuators B, Vol. 68, No. 1, August 2000, pp. 81-87(7)[2] Firebaugh S., Jensen K. Schmidt M., Investigation of High-Temperature Degradation of Platinum Thin Films with an In Situ Resistance Measurement Apparatus, J. Microel. Sys., Vol. 7, No. 1, March 1998

9:00 PM - GG9.2

Ruddlesden-Popper-type Heterostructures in AO-doped SrTiO₃ (A=Sr²⁺,Ca²⁺,Ba²⁺): Structural and Compositional Analysis at the Atomic Level.

Saso Sturm ¹, Miran Ceh ¹
¹Department for nanostructured materials, Jozef Stefan Institute, Ljubljana Slovenia

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Perovskite-based thin films have been extensively studied in recent years, mainly due to their excellent ferroelectric, dielectric and optical properties. For instance, SrTiO₃, an ideal perovskite, reveals a wide range of electrical behavior. In its undoped form it is a paraelectric with a high dielectric constant, while doping with various elements transforms it into superconductor. However, the desired properties of perovskite-based thin films can be suppressed by the formation of defects, which are often initiated during film deposition. Misfit dislocations, formed due to the lattice mismatch between substrate material and the thin film, are such commonly observed defects. In order to reduce the formation of misfit dislocations in perovskite films a variety of uniformly structured buffer layers can be used between the substrate and thin films. In our study, we propose a perovskite-based heterostructred buffer layer, in which the misfit strain would be gradually reduced. A promising candidate for heterostructred perovskite-based buffer layer is a Ruddlesden-Popper-like structure, which we produced by an accommodation of surplus AO in SrTiO₃ (A= Sr²⁺, Ca²⁺, Ba²⁺ ). It is known, that the non-stoichiometry in perovskites (ABO₃) caused by an AO-excess is commonly accommodated by formation of rock-salt type planar faults, also called Ruddlesden-Popper (RP) faults. The resulting heterostructure is composed by alteration of a few unit cells thick perovskite layers (ABO₃) with one layer of an AO-rich rock-salt type structure (RP-faults). By combining quantitative high-resolution transmission electron microscopy (HRTEM) and quantitative high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) of these heterostructures in AO-doped SrTiO₃, we were able to reconstruct their structure and the composition at the atomic level. We found that the structure of RP-faults in the heterostructure remains unchanged regardless of different ions added to SrTiO₃. On the contrary, the composition of these planar faults, as well as the degree of lattice distortions in the perovskite layers and RP-faults, are related to the ion sizes of added ions. Therefore, by introducing A-type cations with different ionic sizes, such as Ca²⁺ and Ba²⁺, the lattice parameters of the heterostructure can be modified, depending on the desired structural properties of a buffer layer between the substrate and various perovskite-based thin films.

9:00 PM - GG9.20

Deposition of Fluorine Doped Tin Oxide Thin Films on Polymers by Plasma Enhanced Chemical Vapor Deposition.

Jerome Pulpytel ¹, Marie Jubaulta ¹, Mickael Redolfi ², Hubert Cachet ³, Farzaneh Arefi-Khonsari ¹
¹LGPPTS, Universite Pierre et Marie Curie, Paris France, ²LIMHP, Universite Paris, Paris France, ³LISE, Universite Pierre et Marie Curie, Paris France

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9:00 PM - GG9.21

Photoelectrical Properties Presented by Indium Zinc Oxide Thin Films and TTFTs.

Goncalo Goncalves ¹, Rodrigo Martins ¹, Elvira Fortunato ¹
¹Materials Science, FCT-UNL, Caparica Portugal

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9:00 PM - GG9.22

Studies of Strains in (Pb,Sr)TiO₃ Films on NdGaO₃ Substrates.

Yuan Lin ¹, Y. Wang ¹, X. Chen ², C. Chen ², A. Bhalla ³, Q. Jia ¹
¹Material Science & Technology Division, Los Alamos National Lab, Los Alamos, New Mexico, United States, ²Texas Center for Superconductivity and Advanced Materials, and Department of Physics , University of Houston, Houston, Texas, United States, ³Materials Research Lab. , Penn. State University, University Park, Pennsylvania, United States

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9:00 PM - GG9.23

Annealing Behavior of (HfO2)_x(Al2O3)_1-x Nanolaminates: Changes in Film Morphology and Structure.

Ramarajesh Katamreddy ^{1 2}, Ronald Inman ², Axel Soulet ², Gregory Jursich ², Christos Takoudis ¹
¹Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois, United States, ², American Air Liquide, Countryside, Illinois, United States

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9:00 PM - GG9.24

Decreasing Splitting of LO-TO Phonons in BaTiO3 Nanoparticles Due to Unit-cell Volume.

Tung-Ching Huang ¹, Wen-Feng Hsieh ¹
¹Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu Taiwan

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9:00 PM - GG9.3

Preparation and Characterization of Ce(1-x)TxO2,(T=Mn,Cr, x = 0.05) by Chemical and Solid State Method.

J Sarala Shanthi ^{1 2}, M Kottiasamy ², K Sethupathi ¹, Mamidanna Ramachandra Rao ^{1 2}
¹Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India, ²Materials Science Research Centre, Indian Institute of Technology Madras, chennai, Tamilnadu, India

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9:00 PM - GG9.4

Design of Single-Source Mixed Acetylacetonate Precursors for Group 13 Oxide Thin Film Growth

Bradley Fahlman ¹, Dan Denomme ¹
¹Department of Chemistry, Central Michigan University, Mount Pleasant, Michigan, United States

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9:00 PM - GG9.5

Low-Temperature Densification and Grain Growth of Bi2O3 - Doped Ceria Gadolinia Ceramics

Jesus Tartaj ¹, Vanesa Gil ¹, Carlos Moure ¹
¹Electroceramics, CSIC, Ceramic and Glass institute, Madrid Spain

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Solid oxide fuel cells, SOFCs, have several advantages as, among others, it can operate not only on hydrogen but also on hydrocarbons and, given that the operating temperatures are sufficiently elevated (800-900C), without using an external reformer, i.e., the reforming of the fuels is carried out within the fuel cell (internal reforming). From a point of view of its commercialization, the above described SOFC present more problems that advantages, as for example, the use of metals as interconnects is not possible at such operating temperature and, therefore, a decrease in the same up to about 550-700C would be desirable. In such operating conditions a wider choice of interconector materials would be possible leading, thus, to a lower cost, higher mechanical strength and, finally, to a longer lifetime of the cell. However, being this so, a device operating in such thermal conditions, i.e., at intermediate temperatures and currently designated as IT-SOFCs, would need the availability of an electrolyte having an ionic conductivity at such temperature range as high as that of YSZ at 850-1000C, and no many ceramic materials are known so far as the most potential candidate for the alternative. Rare earth oxide doped-ceria (RDC) ceramics where R is mainly Y2O3, Gd2O3, and Sm2O3, i.e., YDC, GDC, and SDC, are considered as the best candidate due to their higher ionic conductivity (4 to 9 S/m at 700C). However, two main disadvantages have to be considered as extremely important difficulties before making a final decision for using RDC as the only alternative for electrolyte in IT-SOFCs. One of them is the high electronic conductivity at the reducing side leading to a lower open circuit voltage, along with higher electrochemical oxygen permeation than YSZ. Another one, and the most important, is the difficulty of RDC ceramics to sinter at a temperature reasonably low (1350 to 1400C) with a density level of at least 95-98 % of theoretical density. The use of nanosized GDC powders as an alternative has the strong inconvenient of its rapid shrinkage at low-temperature, becoming this raw material as incompatible with other ceramic components of the SOFC in a co-firing process. Besides this, such nanosized powders are too expensive.We report in this paper, at our best knowledge for the first time in the case of GDC ceramics, the preparation of dense (≥ 98 % of theoretical density) Ce0.9Gd0.1O1.95 ceramic electrolytes sintered at 1200 to 1400C for 4 h, starting from a commercial submicronized powder by using bismuth oxide as a sintering aid. The effect of Bi2O3 additions on the grain-growth process of these dense GDC ceramics will also be reported.

9:00 PM - GG9.6

Thin Film Solid Oxide Fuel Cells on Nanoporous Substrates.

Yong-il Park ¹, Pei-Chen Su ², Gug Ho Yoon ¹, Eun Hyung Kim ¹, Yuji Saito ², Fritz Prinz ²
¹School of Materials & System Engineering, Kumoh National Institute of Technology, Gumi, Kyungbuk, Korea (the Republic of), ²Rapid Prototyping Laboratory, Stanford University, Stanford, California, United States

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9:00 PM - GG9.7

Atomic Layer Deposition of Thin-Film Yttria-Stabilized Zirconia Nanolaminates for Ultra-Thin Solid Oxide Fuel Cell Electrolyte.

Cynthia Ginestra ¹, Paul McIntyre ¹
¹, Stanford University, Stanford, California, United States

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9:00 PM - GG9.8

Highly Near-Infrared Transparent In2O3 Thin-Film Electrodes for Precision Teng-Man Electro-Optic Measurements.

Lian Wang ^{1 2}, Yu Yang ^{1 2}, Tobin Marks ^{1 2}, Zhifu Liu ^{2 3}, Seng-Tiong Ho ^{2 3}
¹Department of Chemistry, Northwestern University, Evanston, Illinois, United States, ²the Materials Research Center, Northwestern University, Evanston, Illinois, United States, ³Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois, United States

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9:00 PM - GG9.9

Defect Luminescence from N-doped ZnO Thin Films.

Hui Wang ¹, Kwong-Chung Lo ¹, Ho-pui Ho ¹
¹Electronic Engineering, The Chinese University of Hong Kong, Hong Kong China

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9:00 PM - GG9: Oxides

GG9.19 Transferred to GG5.3

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9:00 PM - GG9: Oxides

GG9.16 Transferred to GG1.4

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2006-04-20 Show All Abstracts

Symposium Organizers

Dhananjay Kumar North Carolina A&T State University

Valentin Craciun University of Florida

Marin Alexe Max-Planck Institute of Microstructure Physics

Kaushal K. Singh Applied Materials Inc.

GG10: Oxide Films for Magnetic and Optical Applications

Session Chairs

Cammy Abernathy

Thursday AM, April 20, 2006

Room 2018 (Moscone West)

9:15 AM - **GG10.1

Effect of Nonmagnetic Doping on Magneto-Transport Properties of Oxide-Based Zn_1-x(Co,Mn)_xO Dilute Magnetic Semiconductors.

kartik Ghosh ¹, Govind Mundada ¹, Srikanth Manchiraju ¹, Theodore W Kehl ¹, Sandhya Pulugam ¹, Pawan Kahol ¹
¹Physics,Astronomy, and Materials Science, Missouri State University, Springfield, Missouri, United States

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9:45 AM - GG10.2

Improved Photoluminescence Yield by Controlling Erbium Doping Level and Its Distribution in Yttrium Oxide Thin Films.

Trinh Van ¹, John Hoang ¹, Jane Chang ¹
¹Chemical & Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California, United States

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Miniaturizing the erbium-doped optical fiber amplifier (~20 m in length) into a small, compact planar optical amplifier that can be integrated with other optical and electronic devices on a single chip (optoelectronics) offers great promise in optical communication as an alternative to the electronic technology. Though SiO2 has been widely used as a host material for Er-doped optical amplifiers, its low solubility for Er ions limits its application in miniaturized devices. Another limiting factor in miniaturizing these amplifiers is that, while a high concentration of Er ions are desired to achieve the necessary gain of the device, the conventional method for Er incorporation, ion implantation followed by a high temperature annealing, typically results in Er clustering and precipitate formation and quenches the Er luminescence. In this study, we synthesized yttrium oxide (Y2O3) as the host material since it has an identical crystal structure and a very similar lattice constant to that of erbium oxide (Er2O3), allowing for a much higher Er concentration to be incorporated, compared to that in the SiO2 host. We demonstrated radical-enhanced atomic layer deposition (RE-ALD) as a superior method for Er incorporation with spatial control. With an appropriate choice of precursor chemistry, we were able to synthesize Er-doped Y2O3 thin films at temperatures below 400 °C. In addition, the Er doping level and its distribution in the Y2O3 lattice were effectively controlled by combining RE-ALD of Y2O3 and Er2O3 in an alternating fashion, confirmed by X-ray photoelectron spectroscopy and extended X-ray absorption fine structure. Incorporation of optically active Er3+ in the Y2O3 host with concentration that is at least three orders of magnitude higher than the Er solubility limit in SiO2 was achieved, thus making it possible to observe significant photoluminescence (PL) at room temperature for a fairly thin film (~50 nm). Specifically, the room-temperature PL at 1.54 micron characteristic of the Er intra 4f transition showed various well resolved Stark features, indicating the proper incorporation of Er in the Y2O3 host. The result is promising, since the film is fairly thin and no annealing at high temperature is needed to activate the Er ions. The effective absorption cross section for Er3+ ions incorporated in Y2O3 was determined to be ~ 10-18 cm2, about three orders of magnitude larger than the direct optical absorption cross section reported for Er3+ ions in the SiO2 host.[1] Direct measurement of the Er absorption cross section by cavity ringdown spectroscopy was recently performed to further assess the luminescence mechanism responsible for this enhanced PL efficiency.[2][1] T.T. Van and J.P.Chang, Appl. Phys. Lett. 87, 011907 (2005).[2] W.M.M. Kessels, B. Hoex, I.M.P. Aarts, T.T. Van, J.P. Chang, H. Mertens, A. Polman, and M.C.M. van de Sanden, abstract submitted to MRS 2006 Spring meeting.

10:00 AM - GG10.3

Studies of Interfacial Optical and Electrical Properties on Transparent Dielectrics/ZnO Systems.

Ran Shi Wang ¹, Jin An ¹, H.C. Ong ¹
¹Physics, The Chinese University of Hong Kong, Hong Kong Hong Kong

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10:15 AM - GG10.4

Combinatorial Study on In-Ga-Zn-O Semiconductor Films as Active-channel Layers for Thin-film Transistor.

Tatsuya Iwasaki ¹, Naho Itagaki ¹, Tohru Den ¹, Hideya Kumomi ¹, Kenji Nomura ², Toshio Kamiya ^{2 3}, Hideo Hosono ^{2 3}
¹Canon Research Center, CANON INC., Tokyo Japan, ²ERATO-SORST, Japan Science and Technology Agency, Tokyo Institute of Technology, Yokohama Japan, ³Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama Japan

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Thin-film transistors (TFTs) using oxide semiconductors are promising devices for flat-panel displays and system-on-glass due to their good device performance, high optical transparency, and low process temperature. Recently, great interest has been directed toward TFTs with amorphous-InGaZnO₄ channel layers since they can be fabricated at room temperature on flexible substrates and exhibit high saturation mobility of 6-9cm²V^-1sec^-1 [1]. Here we report the chemical composition dependence of In-Ga-Zn-O film properties and the device characteristics using these films as the TFT channel layers. The In-Ga-Zn-O films were prepared by radio-frequency magnetron sputtering method at room temperature in mixed-gas atmosphere of argon and oxygen. The combinatorial synthesis technique was adopted to study compositional dependence of In-Ga-Zn-O films efficiently. The newly developed co-sputtering equipment with three kinds of cathodes (In₂O₃, Ga₂O₃ and ZnO), which makes the compositionally graded film with uniform thickness across the 4-inch substrate, was effectively utilized. The chemical composition, the crystallinity, the electrical conductivity and the optical transmission spectrum were evaluated for the compositional libraries of In-Ga-Zn-O films. Further, we investigated the device characteristics of TFTs having the In-Ga-Zn-O channel layers with various compositions. In order to study the In-Ga-Zn-O chemical composition dependency in the channel layer of TFTs, we applied the combinatorial scheme to the device production. The TFT libraries, having various In-Ga-Zn-O layers as the channel layer, were fabricated by using above compositionally graded films and photolithography techniques. Over 10000 kinds of TFTs were fabricated on a substrate at a time and compared with each other. The TFT libraries enabled us to systematically survey the device characteristics of TFTs in wide compositional range of channel material. It is found that the TFT characteristics are very sensitive to the chemical composition ratio of In:Ga:Zn and oxygen partial pressure during deposition. Some devices exhibited good performance of the field-effect mobility of ~10 cm²V^-1sec^-1 and on-to-off current ratio of ~10⁸. The relationship between the device characteristics and the film properties for various chemical compositions of In-Ga-Zn-O are discussed. Finally, based on the experimental results, we propose a favorable composition of In-Ga-Zn-O films for active channel layers of transparent TFTs.[1] K.Nomura, H.Ohta, A.Takagi, T.Kamiya, M.Hirano and H.Hosono, Nature, 432, 488-492 (2004).

10:30 AM - GG10.5

Characterization of Glancing Angle Deposition Thin Film Optical Filters with Engineered Index Profiles.

James Gospodyn ¹, Peter Hrudey ¹, Michael Brett ¹, Jeremy Sit ¹
¹Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada

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The thin film fabrication technique glancing angle deposition (GLAD) produces porous, columnar films by exploiting highly oblique angle deposition. Central to the GLAD technique is in situ control of the substrate orientation which allows the growing columns to be sculpted into various morphologies including helices and tilted or vertical columns. By using a rapid rotation in the substrate, the films are composed of isolated columns oriented normal to the substrate. Subsequently, by introducing an exponential decrease in the incoming flux angle as the film grows, we can achieve a second layer but of a higher film density. Thus a film grown in this case is composed of a low-index layer of vertical isolated columns, which is capped-off by a high-index, solid layer of the same material. In our method, by repeating this sequence, we can form a multiple-period high-low dielectric stack. By using this technique, we have a one deposition process for achieving a high-low dielectric stack. Furthermore, we can engineer the thickness and periodicity of the films, as well as the form of the periodicity from abrupt high-low (dielectric stacks), to a sinusoidal index variation (rugate filters).In this study, we examine both high-low index and rugate filter films composed of SiO₂, a simple inorganic optical material, and Eu-doped Y₂O₃, an inorganic phosphor. We characterize the index profile of the films using spectroscopic Mueller matrix ellipsometry and examine the morphology of the columns throughout the growth of the film through scanning electron microscopy studies. This leads to a complete description of the optical properties of these films as a function of wavelength. We also examine how modifying the index profile of Y₂O₃:Eu films affects their photoluminescence output – studies here include the effect the differences between high-low stacks compared with sinusoidal index variation, the emissive output dependence on the number of periods for a given periodicity, as well as the effect that the periodicity has on the luminescence output.

10:45 AM - GG10.6

Novel Low-Driving-Voltage Organic Electro-Optic Modulators using Transparent Conducting Oxides as Electrodes.

Lian Wang ^{1 2}, Yu Yang ^{1 2}, Tobin Marks ^{1 2}, Guoyang Xu ^{2 3}, Zhifu Liu ^{2 3}, Boyang Liu ^{2 3}, Seng-Tiong Ho ^{2 3}
¹Department of Chemistry, Northwestern University, Evanston, Illinois, United States, ²the Materials Research Center, Northwestern University, Evanston, Illinois, United States, ³Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois, United States

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11:00 AM - GG10:Magneto

BREAK

GG11: ZnO Oxide Films for Optoelectronic Applications

Session Chairs

Kartik Ghosh

Thursday PM, April 20, 2006

Room 2018 (Moscone West)

11:30 AM - **GG11.1

Synthesis of ZnO Based Exotic Nanostructures Using a Novel Sol-gel Technique.

Michael Snure ¹, Ashutosh Tiwari ¹
¹Materials Science & Engineering, university of utah, Salt Lake City, Utah, United States

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12:00 PM - GG11.2

Trace Detection and Related Solubility Issues in MOCVD Grown Pure and Mixed-phase ZnO Films

Laxmikant Saraf ¹, Zheming Wang ¹, V Shutthanandan ¹, Scott Lea ¹, S Heald ¹, M Engelhard ¹, C Wang ¹, P Nachimuthu ¹, J Swoboda ¹, S Thevuthasan ¹, S Chambers ¹
¹, Pacific Northwest National Laboratory, Richland, Washington, United States

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12:15 PM - GG11.3

Preparation of Atomically Smooth ZnO layer on GaN Template by Laser Deposition.

Takeshi Okato ^{1 2}, Minoru Obara ¹, Menno Kappers ², Mark Blamire ²
¹Electronics and Electrical Engineering, Keio University, Yokohama Japan, ²Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom

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12:30 PM - GG11.4

Formation Of Impurity Complexes During The Growth Of Undoped And Nitrogen Doped Zinc Oxide.

Norbert Nickel ¹, Felice Friedrich ¹, Pierre Galtier ², Jean-Francois Rommeluere ²
¹, Hahn-Meitner-Institut Berlin, Berlin Germany, ², CNRS-LPSC, Meudon France

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GG12: Transparent Conducting Oxide Films

Session Chairs

Jean-Pierre Locquet

Thursday PM, April 20, 2006

Room 2018 (Moscone West)

2:30 PM - **GG12.1

Optimization of Transparent Conducting Amorphous In-Zn-O (a-IZO) Thin Films

John Perkins ¹, Maikel van Hest ¹, Matthew Dabney ¹, Lynn Gedvilas ¹, Brian Keyes ¹, Bobby To ¹, David Ginley ¹, Matthew Taylor ², Dennis Readey ²
¹, National Renewable Energy Lab., Golden, Colorado, United States, ², Colorado School of Mines, Golden, Colorado, United States

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3:00 PM - GG12.2

Band Structure and Optical Properties of n-type and p-type Transparent Conducting Oxides.

Suhuai Wei ¹
¹, National Renewable Energy Laboratory, Golden, Colorado, United States

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3:15 PM - GG12.3

Some Studies on Molybdenum Doped Indium Oxide Thin Films rf Sputtered at Room Temperature.

E. Elamurugu ¹, P Barquinha ¹, A Pimentel ¹, R Martins ¹, E Fortunato ¹
¹Department of Materials Science, University of New Lisbon, Monte de Caparica, Setubal, Portugal

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3:30 PM - GG12.4

Surface States and Segregation of Tin on tin-doped Indium Oxide Surfaces.

Yvonne Gassenbauer ¹, Andreas Klein ¹
¹Materials Science, Darmstadt University of Technology, Darmstadt Germany

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In this contribution we will demonstrate photoelectron spectroscopy (PES) in combination with in-situ sample preparation as a powerful tool to examine the correlation between electronic and chemical properties of oxide surfaces. Tin-doped indium oxide (ITO) as an example, is a degenerate semiconductor showing high transparency in the visible region and a high electrical conductivity. It is widely used as electrode material in optoelectronic devices, for example in organic light emitting diodes (OLEDs), flat panel displays or thin film solar cells. The ITO electronic surface properties strongly correlate with chemical and structural properties. While optical measurements showed a strong Burstein-Moss shift indicating a Fermi level above the conduction band minimum in the bulk of the material, it can be shown using PES that the surface Fermi level is located inside the forbidden band gap at the surface. Hence a surface depletion layer is present having its origin in a high density of surface states around the Fermi-level. This is most likely related to not fully coordinated In or Sn atoms at the surface. The electrostatic potential drop at the surface leads to segregation of Sn dopants, which are obviously mobile enough to change their concentration on the time scale of 1 hour at temperatures as low as 300°C. The surface properties of ITO can be modified by changing preparation conditions using magnetron sputtering or by applying post-deposition treatments. Under reducing preparation conditions, or by exposure to reducing atmospheres after deposition, the density of surface states can be increased which in turn leads to an increase of Sn content at the surface. Electronically, the treatments change the position of the Fermi-level with respect to the band edges with an associated change of work function of the same magnitude. No change of the surface dipole is observed. In contrast, ozone treatment, which is a common method to clean ITO surfaces for organic LEDs, results in a change in Fermi level position and in surface dipole.

3:45 PM - GG12.5

Boron Doping Effects on the Electro-optical Properties of Zinc Oxide Thin Films Deposited by Low-Pressure Chemical Vapor Deposition Process.

Steinhauser Jerome ¹, Seung Yeop Myong ¹, Sylvie Fay ¹, Romain Schluchter ¹, Evelyne Vallat ¹, Alain Rufenacht ², Arvind Shah ¹, Christophe Ballif ¹
¹PV-Lab, Institute of Microtechnology, Neuchatel Switzerland, ², Institute of Physics, Neuchatel Switzerland

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4:00 PM - GG12:Transparent

BREAK

GG13: Growth and Characterization of Oxide Films

Session Chairs

David Christen

Thursday PM, April 20, 2006

Room 2018 (Moscone West)

4:15 PM - **GG13.1

Study of Oxide Film Growth and Interface Processes Using Integrated Physical Vapor Deposition and In Situ Ion, Electron, and Photon-Based Spectroscopy Techniques.

O. Auciello ¹, L. Zhong ¹, B. Kabius ¹, J.P. Allain ², A. Hassanein ², M. Nieto ², V. Titov ², E.A. Irene ³
¹Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, ²Energy Technology Division, Argonne National Laboratory, Argonne, Illinois, United States, ³, University of North Carolina, Chapel Hill, North Carolina, United States

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4:45 PM - GG13.2

Adsorption of Methane on the MgO(100) Surface: Insight from Inelastic Neutron Scattering and First-Principles Calculations

Michael Drummond ¹, Bobby Sumpter ¹, William Shelton ¹, John Larese ^{2 3}
¹Computer Science & Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, ²Chemistry Department, University of Tennessee, Knoxville, Tennessee, United States, ³Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States

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5:00 PM - GG13.3

Spectroscopic Study of Titanium Oxide Thin Films at Low Temperatures by X-ray Diffraction, Raman Scattering, Fourier Transform Infrared Spectroscopy and Photoluminescence.

Beng Kang Tay ¹, Zhiwei Zhao ¹
¹School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore Singapore

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5:30 PM - GG13.5

Correlations between Microstructure and Resistive Switching in Pt/TiO2/Pt Thin Film Capacitors – An Approach by TEM Investigations

Herbert Schroeder ¹, Doo Seok Jeong ¹
¹IEM / IFF and CNI, Forschungszentrum Juelich GmbH, Juelich Germany

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Resistive non-volatile memories are serious candidates for substituting conventional charge-based DRAMs in future ultra-large scale-integrated memory chips in a simple cross-bar architecture. A large variety of material candidates is presently under discussion such as magnetic RAM, phase change materials, single molecules, polymers and other organic insulating materials, but also functional oxides, e.g. ferroelectric and paraelectric oxide thin films. There are numerous experimental (leakage) current data published in the literature for each material class demonstrating the switchable memory effect but there is no agreement on the working mechanism, especially for the oxides. To a large extent this is due to the lack of microstructural information on the changes during formation and switching of the devices. Among the suggested mechanisms the creation and destruction of highly conductive paths, so-called filaments, is favored by many groups. If these effects are connected with microstructural changes these may be observable in a transmission electron microscope (TEM) and correlated to resistance changes.Therefore, in this contribution we present a rather seldom used approach for a TEM experiment to observe the microstructure of a metal/insulator/metal (MIM) capacitor structure before and after (ex-situ) as well as during (in-situ) resistive switching due to an applied external voltage or current. A special TEM sample holder has been developed allowing controlled application of temperature (RT to 300°C) with a heating stage and of voltage (current) as a part of a 4-point resistance measurement set-up for ex- and in-situ experiments. This is combined with a special TEM sample preparation method, the so-called window-technique, for which the silicon substrate is etched away from the backside, so that no thinning of the MIM thin film structure is necessary at all (which is an advantage as the oxides are known to be very sensitive to damage introduced by methods such as ion-milling). Special electrode configurations have been designed to allow nearly undisturbed TEM observation of the switching insulator. Identical samples are also investigated ex-situ in conventional switching experiments to identify the influence of the special TEM environment (high vacuum, irradiation with energetic electrons). Examples for first microstructural observations in a (Pt/amorphous TiO2 thin film/Pt) stack on the resistive switching will be presented.

5:45 PM - GG13.6

Laser Heating, A Challenging New Technology For Small Substrates In Oxide Deposition Processes.

W. Stein ¹
¹, SURFACE System & Technology GmbH &CoKG, Huckelhoven Germany

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GG14: Poster Session: Multifunctional Oxide Films and Devices

Session Chairs

Kaushal Singh

Friday AM, April 21, 2006

Salons 8-15 (Marriott)

9:00 PM - GG14.1

TiO2 Film Formation Behavior in Micro Arc Processed Ti and Ti-6Al-4V Alloys.

Young-Keun Shin ¹, Anatoli Mamaev ², Vera Mamaeva ², Seung-Young Park ³, Yun-Mo Sung ³
¹Mater. Sci. & Eng., Daejin Univ, Pochun Korea (the Republic of), ²Ceramic Coating Lab, ISPMS, Tomsk Russian Federation, ³Materials Sci. & Eng., Korea University, Seoul Korea (the Republic of)

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9:00 PM - GG14.10

Electrical Characteristics of BaxSr1-xTiO3(BST) Capacitors Implemented with Ti-Al Electrodes

Thottam Kalkur ¹
¹Dept. of ECE, University of Colorado, Colorado Springs, Colorado, United States

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9:00 PM - GG14.11

Orientation Dependence of Strontium-doped Lead Zirconate Titanate (PSZT) Thin Films on RF Magnetron Sputtering Conditions.

Sharath Sriram ¹, Madhu Bhaskaran ¹, Anthony Holland ¹, Geoffrey Reeves ¹
¹Microelectronics and Materials Technology Centre, School of Electrical and Computer Engineering, RMIT University, Melbourne, Victoria, Australia

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9:00 PM - GG14.12

HRTEM Observation in Cr-doped SrZrO₃ Perovskite Thin Films.

Hwan-Soo Lee ¹, David Laughlin ², Paul Salvador ², James Bain ¹
¹Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, ²Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States

Show Abstract

In recent years, films of Cr-doped SrZrO₃ (Cr:SZO) perovskite oxides¹, along with other oxide systems,² have attracted significant interest as potential memory materials for cross-point non-volatile memory. In this geometry, a film of the material would be sandwiched between two conducting electrodes, (often with SrRuO₃ [SRO] as the bottom electrode to permit epitaxial film growth of the Cr:SZO). In this work, epitaxial Cr:SZO thin films deposited directly on (001) SrTiO₃ (STO) substrates were studied by transmission electron microscopy (TEM). The SRO bottom electrode was eliminated to simplify the analysis, but, due to the structural similarities of the SRO layers (a = 0.393 nm) and STO substrates (a = 0.3905 nm), it is expected that the observations for films directly on STO may apply to films on SRO bottom electrodes as well.Undoped SZO is stable at room temperature in the orthorhombic (Pnma) phase, with the following lattice parameters: a=0.5814, b=0.8196, and c=0.5792 nm.³ This phase is sometimes described using a pseudo-cubic set of basis vectors, having a lattice parameter, a'=0.409 nm, and with the a and c axes of the orthorhombic unit corresponding to the < -101 > and < 101 > in the pseudo-cubic reference frame. In TEM plan view images, lattice plane fringes associated with an in-plane period of ~0.82 nm were observed, indicating two variants of this Pnma phase in the Cr:SZO films, with domains having the b axis parallel to either the [100] or the [010] in-plane directions of the substrate. Consistent with this, reflections at half-integral reciprocal points of the pseudo-cubic Cr:SZO a'(100) lattice planes were observed in the corresponding electron diffraction pattern. However, the fact that there are no reflections at half-integrals of a'(110) planes indicates that the b axes lie only in the film plane, not out of the plane. This lack of normal b orientation is attributed to a minimization of lattice mismatch, since a larger lattice mismatch (5.3 %) between the Cr:SZO and the STO substrate is expected along the a direction than those (4.9%) in b and c directions.In addition to these orientational features, high-resolution TEM (HRTEM) images of the cation columns projected along the viewing direction a' [001] at a higher magnification reveal a consistent displacement of the cations by 0.03-0.04 nm along the pseudo-cubic a' [010] direction (which corresponds to the orthorhombic b [010] direction). Additionally, in some regions, periodic cation displacements along the pseudo-cubic [110] direction were observed. This last feature structure could indicate oxygen/vacancy ordering but more detailed structural examinations are needed to make this determination.References1A. Beck et al., Appl. Phys. Lett., 77, 139 (2000).2A. Baikalov et al., Appl. Phys. Lett., 83, 957 (2003).3A. Ahtee et al., Acta Cryst. B32, 3243 (1976).

9:00 PM - GG14.13

High Temperature Ferromagnetism in Transition Metal doped Lanthanide Oxides

Ashutosh Tiwari ¹
¹Materials Science & Engineering, university of utah, Salt Lake City, Utah, United States

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9:00 PM - GG14.14

WITHDRAWN 4/7/06 Low Resistivity ZnO-Based Thin Films On Aluminum Nitride Substrates.

Yeon Hwa Jo ¹, Dong joo Shin ¹, Hyun Jae Kim ², Yong S Cho ¹
¹School of Advanced Materials Engineering, Yonsei Univ., Seoul, 120-749, Korea (the Republic of), ²Department of Electrical and Electronic Engineering, Yonsei Univ., Seoul, 120-749, Korea (the Republic of)

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9:00 PM - GG14.17

Thermoelectric Properties of Nano-structure Controlled Sm_2-xCe_xCuO₄ Thin Films.

Yusuke Ichino ¹, Koji Yamazaki ¹, Yutaka Yoshida ¹, Yoshiaki Takai ¹
¹Dept. of Energy Engineering and Science, Nagoya University, Nagoya Japan

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We have studied an improvement of thermoelectric properties of RE_2-xM_xCuO₄ (RMCO; RE=light rare earths, M=Ce, alkaline earths) materials so far. Although the RMCO is well known as the superconductor, the excellent thermoelectric properties of RMCO have also been reported. In order to enhance the thermoelectric properties of RMCO, we have prepared the RMCO thin films and controlled the crystallographic orientation, carrier concentration and introduction of nano-structures. In particularly, we expect the decrease of thermal conductivity due to the phonon scattering at crystalline defects introduced by nano-structure. In this report, we will discuss the effect of substrate with nano-structure in Sm_2-xCe_xCuO₄ (SCCO) films on the thermoelectric properties.The SCCO films and nano-structures were fabricated using the pulsed laser deposition (PLD) method on SrTiO₃ (STO) single crystalline substrates. In order to form the nano-structure on STO, thin CeO₂ layer was deposited, and then, annealed at 900~1000°C in O₂ gas flow. After this heat treatment, the nano-dotted and nano-porous structures, which were made of CeO₂, were appeared on the STO substrates with a height of less than 50 nm. The SCCO films were prepared on the nano-structural substrate under the conditions of growth temperature 840°C, oxygen pressure 0.4 Torr and laser energy 1.0 J/cm². Orientation and crystalline phases were checked by x-ray diffraction. Surface morphologies of films were observed by atomic force microscopy (AFM). Carrier concentration and mobility of films was confirmed by Hall effect measurement.We measured the nano-structural effect on the power factors (PF) of SCCO films. As a result, PF showed a maximum at a certain height of the nano-structures, and the value was 0.66×10^-3 W/K²m. This improvement of PF occurs by the high conductivity in the SCCO film due to the high mobility of carrier. From the SCCO thickness dependence of mobility, we found that the mobility of thin film was higher than that of thick film. Because the mobility of SCCO films tends to be improved with increase of Ce content, we argued that the high mobility was achieved by a formation of high Ce concentration layer at film-substrate interface.This research was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (B), 16360479, 2005.

9:00 PM - GG14.18

Current Percolation in Two-dimensional Vanadium Dioxide Thin Films.

John Rozen ¹, Rene Lopez ², Richard Haglund ^{2 1}, Leonard Feldman ^{2 1}
¹Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee, United States, ²Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee, United States

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9:00 PM - GG14.19

Effect of Polyvinylpyrrolidone Molecular Weight on the Critical Thickness, Densification and Properties of PLZT Films.

Zehui Du ¹, Jan Ma ¹
¹school of materials science and engineering, Nanyang Technological University, Singapore Singapore

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9:00 PM - GG14.2

Effects of Sputtering Power and Annealing Temperature on the Properties of Sc-doped ZnO Thin Films.

Ming Hua Shiao ¹, Cheng-Chung Jaing ², Yu-Jia Huang ³, Chien-Ying Su ¹, Chih-Jung Lu ⁴
¹, Instrument Technology Research Center, Hsinchu Taiwan, ²Department of Optoelectronic System Engineering, Ming Hsin University of Science & Technology, Hsinchu Taiwan, ³Department of Electronic Engineering, Ming Hsin University of Science & Technology, Hsinchu Taiwan, ⁴Department of Materials Engineering, National Chung Hsing University, Taichung Taiwan

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9:00 PM - GG14.21

Reversible Tunability of Crystalline Perovskite-like Structures and Physial Properties in Strontium Titanate.

Dirk Meyer ¹, Alexandr Levin ¹, Tilmann Leisegang ¹, Emanuel Gutmann ¹, Marianne Reibold ¹, Peter Paufler ¹, Reiner Dietsch ²
¹Physics, Dresden University of Technology, Dresden Germany, ², AXO Dresden, Dresden Germany

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9:00 PM - GG14.22

Growth Mechanisms in the Epitaxy of Manganite Films and Control of Surface Roughening

Ingrid Infante ¹, Florencio Sanchez ¹, Ulrike Luders ¹, Llibertat Abad ¹, Josep Fontcuberta ¹
¹, ICMAB-CSIC, Bellaterra Spain

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Understanding the growth mechanisms in the epitaxy of a material is critical to control its (nano)microstructure and its surface morphology. The great efforts that have been done to this research in the field of semiconducting materials are in sharp contrast with the reduced attention paid to the growth of oxides. In the particular case of manganites, enormous efforts are concentrated to investigate their properties and to use them to fabricate magnetic tunnel junctions. These devices require two-dimensional (2D) growth of epitaxial films and ultra-flat surfaces, but paradoxically little is known about the growth processes. Moreover, it is commonly observed that three-dimensional islands appear above a relatively low thickness of the manganite films. Clearly, understanding and controlling growth of manganites, and of complex oxides in general, is a necessary step towards its funcionalization.We have investigated the growth mechanisms and surface morphology of La0.67Ca0.33MnO3 epitaxial films on SrTiO3(001) substrates. It is found that at early growth stages, in nanometric films, a layer-by-layer mechanism dominates, which results in step and terrace surface morphology. Upon further growth, the flat surface becomes unstable when large 2D islands form. A step-edge energy barrier induces an anisotropic adatom kinetics that reduces downhill adatom current and thus favours 2D nucleation on top of the islands. As a result, there is an evolution with growth to mound-like structures of increasing height. Critical thickness for mound formation and average mound separation can be tuned by substrate miscut angle and growth temperature. We demonstrate that mounds do not appear if the growth is by step flow mechanism, although there is a marked step meandering. We analyze the results and we discuss on methods to obtain stable two-dimensional growth in thicker films. In addition, knowing the influence of the growth mechanism into film nanostructure and its properties, we present detailed characterization of the strain state and the magnetic properties of films of varied thickness. The structural and magnetic data are discussed in connection with the morphology and the roughness transition.

9:00 PM - GG14.23

Epitaxial Pt(111) Thin Films on Si(111) Substrates with γ-Al₂O₃(111) as Buffer Layer.

Mikinori Ito ¹, Kazuaki Sawada ¹, Makoto Ishida ¹
¹Electrical and Electronic Engineering, Toyohashi University of Technology, Toyohashi Japan

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(111)-oriented epitaxial Pb(Zr,Ti)O₃ (PZT) films around morphotropic phase boundary composition on SrRuO₃(111)/SrTiO₃(111) substrates exhibit larger piezoelectric response more than other orientations and compositions^[1]. Therefore, (111)-oriented epitaxial PZT films are attracting much attention for micro-electro-mechanical systems (MEMS) and sensor applications. However, there have been hardly any reports realized such PZT films on Si substrates. For this achievement, it is required (111)-oriented epitaxial bottom electrode on Si substrates. In addition, the electrical and physical properties of the PZT films are strongly affected by the surface roughness and crystal quality of bottom electrode. Therefore, the fabrication of smooth and good crystalline quality epitaxial bottom electrodes are demanded. In this study, we report the atomically flat epitaxial Pt(111) films grown on Si(111) substrate using γ-Al₂O₃(111) as buffer layer. γ-Al₂O₃(111) thin films epitaxially grown by molecular beam epitaxy (MBE) on 4inch Si(111) substrates at 750°C^[2]. Then, Pt thin films were deposited by RF magnetron sputtering with various substrate temperatures ranging from room temperature (RT) to 650°C. The thickness of Pt films was about 100nm. The crystal structure and the crystalline quality of the films were evaluated by reflection high-energy electron diffraction (RHEED) and X-ray diffraction (XRD) measurements. All Pt films were epitaxially grown with completely (111)-orientation on the γ-Al₂O₃(111)/Si(111) . From the XRD rocking curve full widths at half maxima (FWHM) of Pt(111) peak decreases from 2.60° to 0.27° with the increasing of substrates temperature from RT to 650°C. Streaky RHEED patterns were observed at the substrate temperature more than 300°C, which indicates that the films were grown with very smooth surface. Surface morphology was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). The epitaxial Pt(111) film on the γ-Al₂O₃(111)/Si(111) substrate has atomically smooth surface which the RMS value was 0.3nm at the substrate temperature around 500°C. These results showed that the epitaxial Pt films on γ-Al₂O₃(111)/Si(111) substrate have smoother surface than (111)-textured Pt films on conventional Ti/SiO₂/Si substrates. This epitaxial Pt(111)/γ-Al₂O₃(111)/Si(111) structure can be used for realizing (111)-orientated epitaxial PZT films for MEMS and sensor applications. *This work was partially supported by the 21st Century COE Program “Intelligent Human Sensing” from the ministry of Education, Culture, Sports, Science and Technology. [1] S. Yokoyama et al. , Appl. Phys. Lett. 83 (2003) 2408. [2] H. Wado et al. , Appl. Phys. Lett. 67 (1995) 2200.

9:00 PM - GG14.24

Phosphorus Bipolar Doping of ZnO Thin Films Fabricated by Pulsed Laser Deposition.

Arnold Allenic ¹, Yanbin Chen ¹, Guangyuan Zhao ¹, Yong Che ², Bing Liu ², Zhendong Hu ², Xiaoqing Pan ¹
¹Materials Science and Engineering, The University of Michigan, Ann Arbor, Michigan, United States, ², IMRA America, Inc., Ann Arbor, Michigan, United States

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9:00 PM - GG14.25

XAFS Study of Yttrium Doped Nanocrystalline Titania.

Bin Chen ¹, Benjamin Gilbert ², Hengzhong Zhang ¹, Jillian Banfield ^{1 2}
¹Earth & Planetary Science, Univ of California, Berkeley, Berkeley, California, United States, ²Earth Science Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States

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9:00 PM - GG14.26

Development of the Nanostructured Electrode Surface to Improve Li+ Intercalation Rate and Transmissivity in Electrochromic Polymer Devices (ECDs).

Soo Yeun Kim ¹, Chunye Xu ¹, Xiangxing Kong ¹, Lu Liu ¹, Minoru Taya ¹
¹Mechanical Engineering, University of Washington, Seattle, Washington, United States

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9:00 PM - GG14.3

Structural And Electrical Properties Of Piezoelectric ZnO Films Grown By Rf Magnetron Sputtering For Film Bulk Acoustic Resonator.

Gun Hee Kim ¹, Hong Seong Kang ¹, Byung Du Ahn ¹, Sung Hoon Lim ¹, Hyun Woo Chang ¹, Sang Yeol Lee ¹
¹, Yonsei University , Seoul Korea (the Republic of)

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9:00 PM - GG14.4

Surface Modifications of CMR Manganite Thin Films Using Atomic Force Microscope

David Schaefer ¹, Cameron Bolling ¹, John Sunderland ¹, Rajeswari Kolagani ¹, Anthony Davidson ¹, Tyler Bradley ², Bonnie Ludka ³
¹Physics, Astronomy & Geosciences, Towson University, Towson, Maryland, United States, ², Towson High School, Towson, Maryland, United States, ³Physics Department, James Madison University, Harrisonburg, Virginia, United States

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9:00 PM - GG14.5

Fabrication of Calcium Copper Titanate (CaCu3Ti4O12) Thin Films: A Challenging MOCVD Approach.

Graziella Malandrino ¹, Ignazio Fragala' ¹, Raffaellla Lo Nigro ², Roberta Toro ¹
¹Dipartimento di Scienze Chimiche, Universita' di Catania, Catania Italy, ², IMM, CNR , Catania Italy

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9:00 PM - GG14.6

High Quality Indium Tin Oxide Films Grown At Moderate Temperatures By Ultraviolet Assisted Pulsed Laser Deposition

Valentin Craciun ¹, Doina Craciun ², Rajiv Singh ¹
¹Materials Science and Engineering, University of Florida, Gainesville, Florida, United States, ²Laser Department, NILPRP, Bucharest Romania

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9:00 PM - GG14.7

Kinetics Of Silicon Substrate Oxidation During The Deposition Of High-K Layers.

Karthik Ramani ¹, Valentin Craciun ¹, Rajiv Singh ¹
¹Materials Science and Engineering, University of Florida, Gainesville, Florida, United States

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The formation of an interfacial layer during deposition of alternative high-k dielectric materials directly on Si is well documented. Because this layer has a detrimental effect on the overall capacitance of the structure, various processing schemes were pursued to eliminate it or, at least, minimize its thickness. To achieve this goal, many investigations have been performed to understand interfacial layer composition, properties and growth kinetics. This presentation explores the role of the oxygen used during the deposition of various high-k materials such as HfO2, Al2O3, ZrO2 and Y2O3 directly on Si wafers with or without a native oxide on the composition and growth kinetics of the interfacial layer. Several characterization techniques with nanometer-range resolution such as variable angle spectroscopic ellipsometry, angle-resolved x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy with an EELS attachment, and x-ray reflectivity were employed to characterize the thickness, surface and interfacial roughness and chemical bonding of the interfacial layer. The results obtained show that Si oxidation is significantly enhanced by the presence of metallic atoms near the interface region and that the formed interfacial layer is much more permeable to Si atoms outdiffusion than a thermally grown SiO2 layer of similar thickness. This process results in the growth of an interfacial layer that consists of a mixture of SiO2 and the high-k dielectric. For relatively low thicknesses, the presence of such an interfacial layer is beneficial because it increases the layer dielectric constant above that of pure SiO2 and, at the same time, reduces the leakage current through the structure. The main challenge is to keep its thickness below 1 nm to avoid a significant decrease of the overall gate dielectric constant. The use of several metals deposited in a nitrogen containing atmosphere simultaneously with a low temperature UV-assisted nitridation process has been explored to slow down the Si oxidation and especially block Si atoms outdiffusion.

9:00 PM - GG14.8

〈001〉-oriented (Ba,Sr)TiO₃ Films on Polycrystalline Metal Tapes Using Biaxially Oriented MgO/γ-Al₂O₃ Buffer Layers.

Woong Choi ¹, Bo Soo Kang ¹, Quanxi Jia ¹, Vladmir Matias ¹, Alp Findikoglu ¹
¹, Los Alamos National Laboratory, Los Alamos, New Mexico, United States

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9:00 PM - GG14.9

Effect of Transition Metal Ion Doping on the Electrical, Optical and Magnetic Properties of ZnO.

Shubra Singh ^{1 2}, N Rama ^{1 2}, M Ramachandra Rao ^{1 2}
¹Department of Physics, Indian institute of Technology Madras, Chennai, Tamilnadu, India, ²Materials Science Research Centre, Indian Institute of Technology Madras, Chennai, Tamilnadu, India

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2006-04-21 Show All Abstracts

Symposium Organizers

Dhananjay Kumar North Carolina A&T State University

Valentin Craciun University of Florida

Marin Alexe Max-Planck Institute of Microstructure Physics

Kaushal K. Singh Applied Materials Inc.

GG15: Oxide Electronics

Session Chairs

Orlando Auciello

Friday AM, April 21, 2006

Room 2018 (Moscone West)

9:00 AM - **GG15.1

Application Of Uv Excimer Lamps To Thin Film Growth.

Ian Boyd ¹
¹E & E Eng. and London Ctr. for Nanotechnology, University College London, London United Kingdom

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9:30 AM - GG15.2

Atomic Structure and Transport Properties of PrCaMnO Films on (001) and Vicinal SrTiO Substrates.

Christian Jooss ¹, Peter Moschkau ¹, Sebastian Schramm ¹, Christine Borchers ¹, Yimei Zhu ²
¹Institute of Materials physics, University of Goettingen, Goettingen Germany, ², Brookhaven National Laboratory, Upton NY, New York, United States

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9:45 AM - GG15.3

Multifunctional Organic-oxide Buffer Film for Highly Efficient Polymer Light-emitting Diodes.

Tzung-Fang Guo ¹, Fuh-Shun Yang ¹, Zen-Jay Tsai ¹, Ten-Chin Wen ², Sung-Nien Hsieh ², Yaw-Shyan Fu ³
¹Institute of Electro-Optical Science and Engineering, National Cheng Kung University , Tainan Taiwan, ²Department of Chemical Engineering, National Cheng Kung University , Tainan Taiwan, ³Department of Environment and Energy, National University of Tainan, Tainan Taiwan

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10:15 AM - GG15.5

Annealing and Persistent Photoconductivity Effects in Amorphous and Crystalline Vanadium Oxide Films.

D.J. Kekas ¹, A. Dhawan ¹, P. Gollakota ¹, J.F. Muth ¹
¹ECE, North Carolina State University, Raleigh, North Carolina, United States

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10:30 AM - GG15.6

Zinc Oxide: a New “Elastronic” Material.

Elvira Fortunato ¹
¹Materials Science, FCT-UNL, Caparica Portugal

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10:45 AM - GG15: Devices

BREAK

GG16: Solid Oxide Fuel Cells

Session Chairs

Marin Alexe

Friday PM, April 21, 2006

Room 2018 (Moscone West)

11:15 AM - GG16.1

Processing of Dense Nanocrystalline Zirconia Thin Films by Sol-Gel.

Christoph Peters ¹, Andre Weber ¹, Ellen Ivers-Tiffee ¹, Matthias Bockmeyer ², Reinhard Krueger ²
¹Institute of Materials for Electrical Engineering, University of Karlsruhe, Karlsruhe Germany, ², Fraunhofer-Institut fur Silicatforschung ISC, Wurzburg Germany

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11:30 AM - GG16.2

Improved Catalytic Performance in Ultra-Thin Solid Oxide Fuel Cell Electrolytes

Timothy Holme ¹, Fritz Prinz ¹
¹Mechanical Engineering, Stanford University, Stanford, California, United States

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11:45 AM - GG16.3

Preparation and Characterization of Solid Oxide Fuel Cells Cathode Films

Adriana Serquis ^{1 2}, Laura Baque ¹, Nicolas Grunbaum ¹, Fernando Prado ^{1 2}, Alberto Caneiro ¹
¹Temadi, Centro Atomico Bariloche - CNEA, S. C. de Bariloche, Río Negro, Argentina, ², CONICET, Bariloche Argentina

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