Tungsten Diselenide Top-gate Transistors with Multilayer Antimonene Electrodes: Gate Stacks and Epitaxially Grown 2D Material Heterostructures

Yu-Wei Zhang,Chao-Hsin Wu,Chiao-Yun Chang,Shih-Yen Lin,Shu-Wei Chang,Jun-Yan Li,Min-Hsiung Shih

doi:10.1038/s41598-020-63098-1

Abstract

We have demonstrated that with e-beam deposition of a thin Al2O3 layer before atomic layer deposition, a uniform Al2O3 film can be obtained on WSe2/sapphire samples. Device performances are observed for WSe2 top-gate transistors by using oxide stacks as the gate dielectric. By using thermal evaporation, epitaxially grown multilayer antimonene can be prepared on both MoS2 and WSe2 surfaces. With multilayer antimonene as the contact metal, a significant increase in drain currents and ON/OFF ratios is observed for the device, which indicates that high contact resistance between metal/2D material interfaces is a critical issue for 2D devices. The observation of multilayer antimonene grown on different 2D material surfaces has demonstrated less dependence on the substrate lattice constant of the unique van der Waals epitaxy for 2D materials. The results have also demonstrated that stacking 2D materials with different materials plays an important role in the practical applications of 2D devices.

Highlights

Bonds on 2D material surfaces, it is difficult to grow dielectric layers directly on 2D material surfaces
The similar well-stacked layered antimonene film grown on both WSe2 and MoS2 surfaces suggests that van der Waals epitaxy of the same 2D material may occur on different 2D material surfaces
The results demonstrate that the high contact resistance between metal/2D material interfaces is a critical issue for 2D devices

Summary

Introduction

Bonds on 2D material surfaces, it is difficult to grow dielectric layers directly on 2D material surfaces. The other challenge for 2D devices is the choice of metal contacts. Unlike traditional semiconductors such as Si or GaAs, it is difficult to obtain Ohmic contacts between conventional metals adopted for semiconductor devices and 2D materials. It has been proposed in previous publications that by using either graphene or crystallized thin indium (In) films as the contact metals, significant contact resistance reduction can be observed for 2D devices[11,14]. The results have demonstrated that one possible solution for the choice of contact metals for 2D devices may be conducting crystals. By using epitaxially grown multilayer antimonene on WSe2 surfaces as the contact metal, significant increases in drain currents and ON/OFF ratios are observed

Methods

Results

Conclusion