High-Efficiency Photodetector Based On CVD-Grown WS$_2$ Monolayer

Future generation technologies demand high efficiency photodetectors to enable sensing and switching devices for ultrafast communication and machine vision. This require direct-band gap materials with high photosensitivity, high detectivity and high quantum efficiency. Monolayered two- Dimensional (2D)-Semiconductors based photodetectors are the most promising materials for such applications, although experimental realization has been limited due to unavailability of high quality sample. In the current manuscript, we report about WS$_2$ based photodetector having sensitivity of 290 AW-1 upon 405 nm excitation and incident power density as low as 0.06 mW/cm$^2$. The fabricated device shows detectivity of 52*10^14 with external quantum efficiency of 89*10$^3$%. The observed superior photo-response parameters of CVD grown WS$_2$ based photodetector as compared to Si-detectors establishes it capability to replace the Si-photodetectors with monolayered ultrathin device having superior performance parameters.