High-mobility and air-stable single-layer WS2 field-effect transistors sandwiched between chemical vapor deposition-grown hexagonal BN films

M Waqas Iqbal; M Zahir Iqbal; M Farooq Khan; M Arslan Shehzad; Yongho Seo; Jong Hyun Park; Chanyong Hwang; Jonghwa Eom

doi:10.1038/srep10699

High-mobility and air-stable single-layer WS2 field-effect transistors sandwiched between chemical vapor deposition-grown hexagonal BN films

Sci Rep. 2015 Jun 1:5:10699. doi: 10.1038/srep10699.

Authors

M Waqas Iqbal¹, M Zahir Iqbal¹, M Farooq Khan¹, M Arslan Shehzad², Yongho Seo², Jong Hyun Park³, Chanyong Hwang⁴, Jonghwa Eom¹

Affiliations

¹ Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
² Faculty of Nanotechnology &Advanced Materials Engineering and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
³ Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764, Korea.
⁴ Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.

Abstract

An emerging electronic material as one of transition metal dichalcogenides (TMDCs), tungsten disulfide (WS2) can be exfoliated as an atomically thin layer and can compensate for the drawback of graphene originating from a gapless band structure. A direct bandgap, which is obtainable in single-layer WS2, is an attractive characteristic for developing optoelectronic devices, as well as field-effect transistors. However, its relatively low mobility and electrical characteristics susceptible to environments remain obstacles for the use of device materials. Here, we demonstrate remarkable improvement in the electrical characteristics of single-layer WS2 field-effect transistor (SL-WS2 FET) using chemical vapor deposition (CVD)-grown hexagonal BN (h-BN). SL-WS2 FET sandwiched between CVD-grown h-BN films shows unprecedented high mobility of 214 cm(2)/Vs at room temperature. The mobility of a SL-WS2 FET has been found to be 486 cm(2)/Vs at 5 K. The ON/OFF ratio of output current is ~10(7) at room temperature. Apart from an ideal substrate for WS2 FET, CVD-grown h-BN film also provides a protection layer against unwanted influence by gas environments. The h-BN/SL-WS2/h-BN sandwich structure offers a way to develop high-quality durable single-layer TMDCs electronic devices.