Analysis of asymmetrical hysteresis phenomena observed in TMD-based field effect transistors

Abstract

To realize field effect transistors with multi-layered MoS2 and WSe2 (hereafter denoted as MoS2 FET and WSe2 FET), many device instability problems should be surmounted, such as the hysteresis generation of the devices. In order to clarify the mechanism of the asymmetrical hysteresis phenomena observed in the transfer characteristics of the MoS2 and WSe2 FET, the temperature dependencies of their characteristics are analyzed. Based on these analyses, it can be concluded that donor-like traps present in both the SiO2/MoS2 interface and the MoS2 bulk in multi-layered MoS2 FETs, and that acceptor-like traps present in both the SiO2/WSe2 interface, and the WSe2 bulk in multi-layered WSe2 FETs. Furthermore, based on the chemical analyses and the arguments presented in previous studies, we propose that the sulfur vacancy (SV) is the origin of donor-like traps present in MoS2, and the tungsten vacancy (TV) is the origin of acceptor-like traps present in WSe2. This work may provide a potential clue to overcome many practical problems for realization of the transition metal dichalcogenides (TMDs) based FETs.