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

We conducted a comparative investigation of the photoresponse mechanisms in MoS 2 photodetectors by analyzing spatial- and time-resolved photogenerated currents across two-dimensional semiconductor and metal junctions. Our research revealed distinct responses in MoS 2 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 MoS 2 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.