April 7 - 11, 2025
Seattle, Washington
Symposium Supporters
2025 MRS Spring Meeting & Exhibit
CH02.12.06

High Resolution Investigation of WSe2/(Al)GaAs Heterostructures via Electron Beam-Induced Current Mapping

When and Where

Apr 11, 2025
9:15am - 9:30am
Summit, Level 3, Room 343

Presenter(s)

Co-Author(s)

Valerio Piazza1,Michele Zendrini1,Claire Blaga1,Mitali Banerjee1,Anna Fontcuberta i Morral1

Ecole Polytechnique Federale de Lausanne1

Abstract

Valerio Piazza1,Michele Zendrini1,Claire Blaga1,Mitali Banerjee1,Anna Fontcuberta i Morral1

Ecole Polytechnique Federale de Lausanne1
Transition metal dichalcogenides (TMDs) have high spin-orbit coupling [1], exciton funneling [2] and strain modulation [3] which may allow them to be core semiconductors in a wide variety of commercial technologies [4]. As the field expands, new concepts for nano-devices are proposed. Heterostructures made by mixing 2D and other low dimensional materials are of great interest to exploit strain and interface engineering at once [5-7]. A major bottleneck in the field is the clear understanding of nanoscale phenomena dominating the overall functionality of the ensemble. Methodologies based on secondary electron (SE) microscopy offer a great trade-off between probe size and field of view. In this framework, electron beam-induced current microscopy (EBIC) is an appealing candidate to conduct non-destructive investigation of localized electric field, thus enabling engineering of electrically active nanometric elements[8].
Here we demonstrate that EBIC mapping is a powerful method to acquire electrical maps of heterostructures with mixed dimensionality. 2D-3D WSe2-(Al)GaAs heterostructures are fabricated via dry transfer with a PDMS stamp. Binary GaAs and ternary (Al)GaAs with Al content up to 39at.% are grown epitaxially via metalorganic vapour phase epitaxy. The epitaxial growth, performed on (100) Zn:GaAs wafers, allows to obtain both planar layers and 1D horizontal nanostructures grown by selective area method [9,10]. WSe2 flakes with inhomogenous thickness ranging from 1-3L to around 50L are transferred on the III-V epitaxial structures. The fabricated samples are investigated by atomic force microscopy (AFM), photoluminescence (PL) and electron-beam induced current mapping (EBIC). EBIC maps of the 2D-3D heterostructures reveals an electrical built-in field in portions of the heterointerface. This evidence pinpoints the electron-rich nature of our exfoliated WSe2, enriching the debate over the origin of free charges in ultra-thin materials. Correlated analysis with atomic force microscopy (AFM) maps evidence that the dependence of the strength of the field at the heterointerface with the thickness of the WSe2 flake is not monotonic. On the contrary, room temperature micro-photoluminescence (PL) mapping shows increasing quenching of the epilayer emission with increasing WSe2 thickness. Numerical modeling of the collected current enables to get insights into the drift and diffusion of carriers in the ensemble, key to engineer efficient charge transport. By integrating WSe2 on in-plane 1D GaAs nanostructures, we demonstrate the lateral confinement of the electric field in regions as narrow as 250 nm in 2D-1D heterostructures. It is worthy to note that this process allows to obtain deterministatically positioned rectifying elements with sub-micron dimensions. These results prove the potential of nanoscale functional mapping for ultra-thin technologies and pave the way to engineer arrays of nano-heterojunctions.

References
[1] Bangar et al., ACS Appl. Mater. Interfaces 14, (2022)
[2] Moon et al., Nano Lett. 20, (2020)
[3] Manzeli et al., Nat.Rev.Mater. 2, (2017)
[4] Huo et al., J. Semicond. 38, (2017)
[5] Palacios-Berraquero, Nat. Commun. 8, (2017)
[6] Chowdhury, T. et al. ACS Photonics, 8 (2021)
[7] Jasinski et al., 2D Mat. 9, (2022)
[8] Piazza, V. et al. Appl. Phys. Lett. 114, (2019)
[9] Dede, D. et al. Nanotechnology 33, (2022)
[10] Morgan, N. et al. Cryst. Growth Des. 23, (2023)

Keywords

electrical properties | epitaxy | metrology

Symposium Organizers

Tze Chien Sum, Nanyang Technological University
Yuanyuan Zhou, Hong Kong University of Science and Technology
Burak Guzelturk, Argonne National Laboratory
Mengxia Liu, Yale University

Symposium Support

Bronze
LIGHT CONVERSION
Ultrafast Systems LLC

Session Chairs

Mengxia Liu
Yuanyuan Zhou

In this Session