December 1 - 6, 2024
Boston, Massachusetts
Symposium Supporters
2024 MRS Fall Meeting & Exhibit
NM05.17.07

Chemically Tailored and Phase-Selective Growth of 2D Semiconductors via Hybrid Metal-Organic Chemical Vapor Deposition

When and Where

Dec 6, 2024
3:30pm - 3:45pm
Hynes, Level 2, Room 207

Presenter(s)

Co-Author(s)

Zhepeng Zhang1,2,Lauren Hoang1,Marisa Hocking1,2,Zhenghan Peng1,2,Jenny Hu1,Mihir Pendharkar1,2,Elijah Courtney1,2,Gregory Zaborski Jr.1,Pooja Reddy1,Johnny Dollard1,Marc Kastner1,2,3,David Goldhaber-Gordon1,2,Tony Heinz1,2,Eric Pop1,Andrew Mannix1,2

Stanford University1,SLAC National Accelerator Laboratory2,Massachusetts Institute of Technology3

Abstract

Zhepeng Zhang1,2,Lauren Hoang1,Marisa Hocking1,2,Zhenghan Peng1,2,Jenny Hu1,Mihir Pendharkar1,2,Elijah Courtney1,2,Gregory Zaborski Jr.1,Pooja Reddy1,Johnny Dollard1,Marc Kastner1,2,3,David Goldhaber-Gordon1,2,Tony Heinz1,2,Eric Pop1,Andrew Mannix1,2

Stanford University1,SLAC National Accelerator Laboratory2,Massachusetts Institute of Technology3
Two-dimensional (2D) semiconducting transition-metal dichalcogenides (TMDCs) are a leading platform for excitonic physics and next-generation electronics, creating a strong demand to understand their growth, doping, heterostructures and polytypes. Despite significant progress in solid-source (SS-) and metal-organic chemical vapor deposition (MOCVD), further optimization is necessary to grow highly crystalline 2D TMDCs with controlled doping and heterostructures. Here, we report a hybrid MOCVD (Hy-MOCVD) growth method that combines liquid-phase metal precursor deposition and vapor-phase organo-chalcogen delivery to leverage the advantages of both MOCVD and SS-CVD.1 Using our hybrid approach, we demonstrate WS2 growth with tunable morphologies – from separated single-crystal domains to continuous monolayer films – on a variety of substrates, including sapphire, SiO2, and Au. These WS2 films exhibit narrow neutral exciton photoluminescence linewidths down to 27 – 28 meV and mobility up to 34 – 36 cm2V-1s-1 at room-temperature. Through simple modifications to the liquid precursor composition, we demonstrate the growth of V-doped WS2, MoxW1-xS2 alloys, and in-plane WS2-MoS2 heterostructures.
Moreover, rhombohedral polytype (3R) TMDC multilayers exhibit non-centrosymmetric interlayer stacking, which yields intriguing properties such as ferroelectricity, a large second-order susceptibility coefficient χ(2) for nonlinear optics, valley coherence, and a bulk photovoltaic effect. However, phase-selective growth strategies for 3R TMDCs are still underdeveloped and are especially lacking for multilayer films which strongly exhibit the desired optoelectronic characteristics. We facilitate multilayer growth of WS2 by introducing a confined space into the Hy-MOCVD process.2 The confined-space Hy-MOCVD method preferentially grows 3R multilayer WS2 films with thickness up to 130 nm. We confirm the 3R stacking structure via polarization-resolved second harmonic generation characterization and via the threefold symmetry revealed by anisotropic H2O2 etching. The multilayer 3R WS2 shows a dendritic morphology which is indicative of diffusion-limited growth. Multilayer regions with large, stepped terraces enable layer-resolved evaluation of the optical properties of 3R-WS2 via Raman, photoluminescence, and differential reflectance spectroscopy. These measurements confirm the interfacial quality and suggest ferroelectric modification of the exciton energies.
References
[1] Z. Zhang#, L. Hoang#, M. Hocking, Z. Peng, J. Hu, G. Zaborski Jr., P. Reddy, J. Dollard, D. Goldhaber-Gordon, T. F. Heinz, E. Pop and A. J. Mannix*. “Chemically Tailored Growth of 2D Semiconductors via Hybrid Metal-Organic Chemical Vapor Deposition” arXiv:2403.03482 (2024). #These authors contributed equally to this work (Z.Z., L.H.).
[2] Z. Zhang, M. Hocking, Z. Peng, M. Pendharkar, E. D. S. Courtney, J. Hu, M. A. Kastner, D. Goldhaber-Gordon, T. F. Heinz, and A. J. Mannix* “Phase-Selective Synthesis of Rhombohedral WS2 Multilayers by Confined-Space Hybrid Metal-Organic Chemical Vapor Deposition” under review (2024)

Keywords

2D materials | chemical vapor deposition (CVD) (deposition)

Symposium Organizers

Andras Kis, Ecole Polytechnique Federale de Lausanne
Li Lain-Jong, University of Hong Kong
Ying Wang, University of Wisconsin, Madison
Hanyu Zhu, Rice University

Session Chairs

Yi Cui

In this Session