title: High-mobility and air-stable single-layer WS2 field-effect transistors sandwiched between chemical vapor deposition-grown hexagonal BN films.
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.
authors.affiliation: Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: M Waqas
authors.initials: MW
authors.lastname: Iqbal
authors.affiliation: Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: M Zahir
authors.initials: MZ
authors.lastname: Iqbal
authors.affiliation: Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: M Farooq
authors.initials: MF
authors.lastname: Khan
authors.affiliation: Faculty of Nanotechnology &Advanced Materials Engineering and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: M Arslan
authors.initials: MA
authors.lastname: Shehzad
authors.affiliation: Faculty of Nanotechnology &Advanced Materials Engineering and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: Yongho
authors.initials: Y
authors.lastname: Seo
authors.affiliation: Department of Materials Science and Engineering, Chungnam National University, Daejeon 305-764, Korea.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon 305-340, Korea.
authors.forename: Chanyong
authors.initials: C
authors.lastname: Hwang
authors.affiliation: Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: Jonghwa
authors.initials: J
authors.lastname: Eom