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

Future generation technologies demand high efficiencyphotodetectorsto enable sensing and switching devices for ultrafast communicationand machine vision. This requires direct-band gap materials with highphotosensitivity, high detectivity, and high quantum efficiency. Monolayeredtwo-dimensional-semiconductor-based photodetectors are the most promisingmaterials for such applications, although experimental realizationhas been limited due to the unavailability of a high-quality sample.In the current paper, we report about a WS2-based photodetectorhaving a sensitivity of 290 A W-1 upon 405 nm excitationand an incident power density as low as 0.06 mW/cm(2). Thefabricated device shows a detectivity of 52 x 10(14) with an external quantum efficiency of 89 x 10(3) %.The observed superior photoresponse parameters of the CVD-grown WS2-based photodetector as compared to Si-detectors establishits capability to replace the Si-photodetectors with monolayered ultrathindevice having superior performance parameters