Suppression of the Photogating Effect at High Temperatures in SnSe2-based Field-Effect Transistors

The electrical and optoelectronic properties of a SnSe2-based field-effect transistor as a function of temperature and optical excitation are presented. The device was characterized electrically through output and transfer curves measurements in the temperature range of 220 K to 390 K. Transfer measurements confirm n-type conduction. Field-effect mobility, extracted from transfer curves, decreases from 53 to 46 cm2 V⁻1 s⁻1 with increasing temperature. To evaluate the photoresponse, the device was illuminated with a supercontinuum laser. The photocurrent exhibits sublinear dependence on optical power at low temperatures and long characteristic decay time, indicative of a photogating mechanism. Responsivity decreases with temperature, from 1.82 A/W at 220 K to 0.24 A/W at 390 K. The photocurrent dependence on light power becomes progressively more linear at higher temperatures, and a transition from photogating-dominated to photoconductive behavior occurs. The influence of gate voltage on photoresponse was further investigated. A slow decay time of the photocurrent at negative gate voltages confirms persistent photogating, which is mitigated at higher temperatures.