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 WS 2 -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/cm 2 . The fabricated device shows a detectivity of 52 × 10 14 with an external quantum efficiency of 89 × 10 3 %. The observed superior photoresponse parameters of the CVD-grown WS 2 -based photodetector as compared to Si-detectors establish its capability to replace the Si-photodetectors with monolayered ultrathin device having superior performance parameters.