Comparative Investigation of Interplay Between Photothermoelectric and Photoconductive Effects in MoS2 Devices

We conducted a comparative investigation of the photoresponse mechanisms in MoS2 photodetectors by analyzing spatial- and time-resolved photogenerated currents across two-dimensional semiconductor and metal junctions. Our research revealed distinct responses in MoS2 photodetectors that are attributed primarily to the interplay between photoconductive (PC) and photothermoelectric (PTE) effects. The PC-driven photocurrents exhibited higher photoresponsivity, whereas the PTE-driven photocurrents demonstrated a higher on/off ratio and faster response. Slower PC response suggests the presence of trap states in the MoS2 channel, capturing photogenerated charge carriers. In contrast, the PTE effect operated independently of these traps, enabling hot carriers to traverse the channel at high velocities and resulting in a swift photoresponse. These insights provide valuable guidance for designing photodetectors and optimizing their performance by controlling the PC and PTE effects.