Thickness-dependent bandgap and carrier mobility of two-dimensional (2D) van der Waals (vdW) layered materials make them a promising material as a phototransistor that detects light signals and converts them to electrical signals. Thus far, to achieve a high photoresponsivity of 2D materials, enormous efforts have been made via material and dielectric engineering, as well as modifying device structure. Nevertheless, understanding the effect of interplay between the thickness and the carrier mobility to photoresponsivity is little known. Here, we demonstrate the tunable photoresponsivity (R) of 2D multilayer rhenium disulfide (ReS2), which is an attractive candidate for photodetection among 2D vdW materials owing to its layer-independent direct bandgap and decoupled vdW interaction. The gate bias (VG)-dependent photocurrent generation mechanism and R are presented for the channel thickness range of 1.7-27.5 nm. The high similarity between VG-dependent photocurrent and transconductance features in the ReS2 phototransistors clearly implies the importance of the channel thickness and the operating VG bias condition. Finally, the maximum R was found to be 4.1 × 105 A/W at 14.3 nm with the highest carrier mobility of ∼15.7 cm2·V-1·s-1 among the fabricated devices after excluding the contact resistance effect. This work sheds light on the strategy of how to obtain the highest R in 2D vdW-based phototransistors.
Bibliographical noteFunding Information:
This research was supported by the MSIT (Ministry of Science and ICT), Korea, under the ITRC (Information Technology Research Center) support program (No. IITP-2020-2015-0-00385, G.-T.K.) supervised by the IITP (Institute for Information and Communications Technology Planning and Evaluation) and also supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP) (Nos. NRF-2019R1C1C1003467 and NRF-2019K2A9A1A06083674, M.-K.J.) and the Sookmyung Women's University Research Grants (Project No. 1-1903-2002, M.-K.J.).
© 2020 Author(s).
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)