Photosensitivity of bulk and monolayer MoS₂-based two-terminal devices

Transition metal dichalcogenides (TMDCs), such as MoS₂, MoSe₂, WS₂, and WSe_2, have attracted enormous attention owing to their unique electrical and optical properties. A type of material known as TMDC has the MX₂ formula with a direct bandgap in ultra-thin layers and indirect bandgap properties in the bulk. TMDCs have attracted significant research interest due to their use in nano-devices, opto-electronics, and next-generation electronics. In the study, two different MoS₂ devices, Au–bulk MoS₂–Au and Au–monolayer MoS₂–Au, were fabricated, and their photon-induced current–voltage characteristics at different wavelengths (red ≈ 650 nm, green ≈ 532 nm and blue ≈ 450 nm) and values were compared. Additionally, the time-dependent photoresponses of these devices under red light irradiation (wavelength, λ_ex = 650 nm) were analyzed. The Au–monolayer MoS₂–Au device had a higher current response compared with the Au–bulk MoS₂–Au device. These results suggest that single-layer MoS₂ devices could be more efficient and responsive than bulk MoS₂ devices for a variety of applications.