Electron transport of WS$_2$ transistors in a hexagonal boron nitride dielectric environment

TL;DR

This study compares the electrical properties of WS$_2$ transistors on different dielectric environments, revealing that intrinsic disorder limits performance more than extrinsic charge traps, across various thicknesses and temperatures.

Contribution

First comprehensive analysis of WS$_2$ transistor electrical properties on SiO$_2$ and h-BN/SiO$_2$, highlighting intrinsic disorder as the main limiting factor.

Findings

Disorder intrinsic to WS$_2$ limits electrical performance.

Extrinsic factors like charge traps are less influential than intrinsic disorder.

Electrical properties vary with WS$_2$ thickness and temperature.

Abstract

We present the first study of the intrinsic electrical properties of WS$_2$ transistors fabricated with two different dielectric environments WS$_2$ on SiO$_2$ and WS$_2$ on h-BN/SiO$_2$, respectively. A comparative analysis of the electrical characteristics of multiple transistors fabricated from natural and synthetic WS$_2$ with various thicknesses from single- up to four-layers and over a wide temperature range from 300K down to 4.2 K shows that disorder intrinsic to WS$_2$ is currently the limiting factor of the electrical properties of this material. These results shed light on the role played by extrinsic factors such as charge traps in the oxide dielectric thought to be the cause for the commonly observed small values of charge carrier mobility in transition metal dichalcogenides.