Pressure-dependent photoconductivity in two dimensional ReS2

Two-dimensional materials are very sensitive to the surrounding environment because of their high surface-to-volume ratio. Herein, we investigated the electrical properties of few-layer ReS2 back-gated field effect transistors at different pressures. The lowering pressure increases the conductivity and reduces both the Ion/Ioff ratio and the hysteresis width, revealing that air molecules, such as H2O and O2, adsorbed on the ReS2 surface in ambient conditions, act as electron traps. The gas molecules adsorption and desorption processes also impact the photoresponse of the device. This was investigated by looking at the switching behaviour of the device under supercontinuum white laser pulses of different powers and durations in air, low vacuum, and high vacuum.