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Preparation of Large-area Vertical 2D Crystal Hetero-structures Through the Sulfurization of Transition Metal Films for Device Fabrication
Published on: November 28, 2017
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Atomically thin heterostructures based on single-layer tungsten diselenide and graphene.
Yu-Chuan Lin1, Chih-Yuan S Chang, Ram Krishna Ghosh
1Department of Materials Science and Engineering and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
Nano Letters
|November 11, 2014
Summary
We grew high-quality tungsten diselenide (WSe2) monolayers on epitaxial graphene (EG) using advanced techniques. An unexpected interlayer gap barrier was found to affect carrier transport in these 2D heterostructures.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Two-dimensional (2D) layered materials offer tunable electronic and optoelectronic properties.
- Heterogeneous engineering of materials like graphene and transition metal dichalcogenides is key for advanced systems.
- Epitaxial growth is crucial for creating pristine layers and interfaces in heterostructures.
Purpose of the Study:
- To report the direct growth of crystalline, monolayer tungsten diselenide (WSe2) on epitaxial graphene (EG).
- To characterize the quality of WSe2 monolayers and the WSe2/EG interface.
- To investigate carrier transport properties across the WSe2/EG heterostructure.
Main Methods:
- Epitaxial growth of WSe2 on graphene grown from silicon carbide.
- Characterization using Raman spectroscopy, photoluminescence, scanning tunneling microscopy, transmission electron microscopy, and low energy electron diffraction.
- Vertical transport measurements and theoretical calculations (DFT, NEGF) for local density of states (LDOS).
Main Results:
- High-quality WSe2 monolayers were confirmed on EG.
- An atomically sharp interface with near-perfect orientation between WSe2 and EG was observed.
- Vertical transport measurements revealed an additional barrier due to the interlayer gap, beyond the band offset.
Conclusions:
- Direct epitaxial growth enables high-quality WSe2/EG heterostructures.
- The interlayer gap significantly impacts carrier transport, presenting a challenge for device performance.
- Understanding and mitigating this barrier is essential for future 2D electronic and optoelectronic applications.
