Electron transport of WS2 transistors in a hexagonal boron nitride dielectric environment

Freddie Withers,Monica Felicia Craciun,David Christopher Hudson,Saverio Russo,Thomas Hardisty Bointon

doi:10.1038/srep04967

Freddie Withers, Monica Felicia Craciun + Show 3 more

Open Access

https://doi.org/10.1038/srep04967

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Journal: Scientific Reports	Publication Date: May 15, 2014
Citations: 87	License type: CC BY 3.0

Affiliation: University of Exeter

Abstract

We present the first study of the intrinsic electrical properties of WS2 transistors fabricated with two different dielectric environments WS2 on SiO2 and WS2 on h-BN/SiO2, respectively. A comparative analysis of the electrical characteristics of multiple transistors fabricated from natural and synthetic WS2 with various thicknesses from single- up to four-layers and over a wide temperature range from 300 K down to 4.2 K shows that disorder intrinsic to WS2 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.

Highlights

We present the first study of the intrinsic electrical properties of WS2 transistors fabricated with two different dielectric environments WS2 on SiO2 and WS2 on h-BN/SiO2, respectively
The emerging class of atomically thin semiconducting materials formed by transition metal dichalogenides (TMDCs) is showing a plethora of complementary properties to those of graphene that are of interest to fundamental and applied research
At the same time TMDCs have a band gap which is essential for transistor applications and which could enable a new class of atomically thin photo-transistors

Summary

Introduction

A comparative analysis of the electrical characteristics of multiple transistors fabricated from natural and synthetic WS2 with various thicknesses from single- up to four-layers and over a wide temperature range from 300 K down to 4.2 K shows that disorder intrinsic to WS2 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. An ideal choice for such a substrate is hexagonal boron nitride[11], which is a preferred substrate for high quality graphene transistors since it has a very low concentration of charge scattering impurities and is atomically flat[12] To date such a study has not yet been conducted and the consequent lack of knowledge is limiting the potential impact of TMDCs on fundamental and applied research.

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