title: Few-layer HfS2 transistors.
abstract: HfS2 is the novel transition metal dichalcogenide, which has not been experimentally investigated as the material for electron devices. As per the theoretical calculations, HfS2 has the potential for well-balanced mobility (1,800 cm(2)/V·s) and bandgap (1.2 eV) and hence it can be a good candidate for realizing low-power devices. In this paper, the fundamental properties of few-layer HfS2 flakes were experimentally evaluated. Micromechanical exfoliation using scotch tape extracted atomically thin HfS2 flakes with varying colour contrasts associated with the number of layers and resonant Raman peaks. We demonstrated the I-V characteristics of the back-gated few-layer (3.8 nm) HfS2 transistor with the robust current saturation. The on/off ratio was more than 10(4) and the maximum drain current of 0.2 μA/μm was observed. Moreover, using the electric double-layer gate structure with LiClO4:PEO electrolyte, the drain current of the HfS2 transistor significantly increased to 0.75 mA/μm and the mobility was estimated to be 45 cm(2)/V·s at least. This improved current seemed to indicate superior intrinsic properties of HfS2. These results provides the basic information for the experimental researches of electron devices based on HfS2.
authors.affiliation: Department of Physical Electronics, Tokyo Institute of Technology, 152-8552 Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Kanazawa
authors.affiliation: Quantum Nano Electronics Research Center, Tokyo Institute of Technology, 152-8552 Japan.|Metamaterials Laboratory, RIKEN, 351-0198, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Amemiya
authors.affiliation: Metamaterials Laboratory, RIKEN, 351-0198, Japan.|Department of Electrical &Electronic Engineering, Okayama University, 700-8530, Japan.|Innovative Photon Manipulation Research Team, RIKEN, 351-0198, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ishikawa
authors.affiliation: Department of Physical Electronics, Tokyo Institute of Technology, 152-8552 Japan.
authors.forename: Vikrant
authors.initials: V
authors.lastname: Upadhyaya
authors.affiliation: Department of Electrical &Electronic Engineering, Okayama University, 700-8530, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tsuruta
authors.affiliation: Metamaterials Laboratory, RIKEN, 351-0198, Japan.|Innovative Photon Manipulation Research Team, RIKEN, 351-0198, Japan.|Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 226-8502, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Physical Electronics, Tokyo Institute of Technology, 152-8552 Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Miyamoto