High-Efficiency Photodetector Based on a CVD-Grown WS2 Monolayer

Future generation technologies demand high efficiency photodetectors to enable sensing and switching devices for ultrafast communication and machine vision. This requires direct-band gap materials with high photosensitivity, high detectivity, and high quantum efficiency. Monolayered two-dimensional-semiconductor-based photodetectors are the most promising materials for such applications, although experimental realization has been limited due to the unavailability of a high-quality sample. In the current paper, we report about a WS2-based photodetector having a sensitivity of 290 A W–1 upon 405 nm excitation and an incident power density as low as 0.06 mW/cm2. The fabricated device shows a detectivity of 52 × 1014 with an external quantum efficiency of 89 × 103 %. The observed superior photoresponse parameters of the CVD-grown WS2-based photodetector as compared to Si-detectors establish its capability to replace the Si-photodetectors with monolayered ultrathin device having superior performance parameters.