Quantum Transport in Two-Dimensional WS$_2$ with High-Efficiency Carrier Injection Through Indium Alloy Contacts

TL;DR

This study demonstrates low-resistance indium alloy contacts to WS$_2$, enabling efficient carrier injection, high mobility, and quantum transport observations, advancing high-performance 2D TMDC devices.

Contribution

It provides the first detailed quantum transport analysis of WS$_2$ with indium alloy contacts, showing low contact resistance and high mobility at cryogenic temperatures.

Findings

Low contact resistance (~10 kΩ·μm at 3 K)

High carrier mobility (~190 cm²V⁻¹s⁻¹)

Observation of resonant tunnelling

Abstract

Two-dimensional transition metal dichalcogenides (TMDCs) have properties attractive for optoelectronic and quantum applications. A crucial element for devices is the metal-semiconductor interface. However, high contact resistances have hindered progress. Quantum transport studies are scant as low-quality contacts are intractable at cryogenic temperatures. Here, temperature-dependent transfer length measurements are performed on chemical vapour deposition grown single-layer and bilayer WS$_2$ devices with indium alloy contacts. The devices exhibit low contact resistances and Schottky barrier heights (\sim10 k$\Omega$\si{\micro\metre} at 3 K and 1.7 meV). Efficient carrier injection enables high carrier mobilities ($\sim$190 cm$^2$V$^{-1}$s$^{-1}$) and observation of resonant tunnelling. Density functional theory calculations provide insights into quantum transport and properties of the WS$_2$-indium interface. Our results reveal significant advances towards high-performance WS$_2$ devices using indium alloy contacts.