Transient characteristics of back-gated multilayer MoS2 and WSe2 channel n-type metal oxide semiconductor field effect transistors: A comparative study

Abstract

The surface and interface effects of back-gated transition metal dichalcogenide channel MOSFETs are of great importance to device applications. This paper reports the transient current-time (I-t) characteristics of back-gated multilayer MoS2 and WSe2 channel n-type MOSFETs due to the charge trapping into the surface and interface traps of the devices. By investigating the current-voltage and I-t results measured from the devices with a similar structure and bias conditions under ambient and vacuum conditions, we find that the WSe2 devices show more significant surface and interface effects as compared to the MoS2 devices. The comparison of the experimental results with the technology computer aided design simulation shows that a single type trap model can account for the main characteristics of the transient process observed from the MoS2 and WSe2 devices. As compared to the trap on the MoS2 device, the surface trap on the WSe2 device has higher density, lower energy, and smaller trapping time. A further experimental comparison with WS2 devices suggests that the difference is microscopically originated from the chalcogen of Se and S rather than the metal element of Mo and W.