Abstract

      A novel self-powered photodetector based on reduced graphene oxide (rGO)/n-Si p-n vertical heterojunction with high sensitivity and fast response time is presented. The photodetector contains a p-n vertical heterojunction between a drop-casted rGO thin fi lm and n-Si. Contacts between the semiconductor layer (rGO, n-Si) and source drain Ti/Au electrodes allow effi cient transfer of photogenerated charge carriers. The self-powered UV–near infrared photodetector shows high sensitivity toward a spectrum of light from 365 to 1200 nm. Under the 600 nm illumination (0.81 mW cm−2), the device has a photoresponsivity of 1.52 A W−1, with fast response and recover time (2 ms and 3.7 ms), and the ON/OFF ratios exceed 104 when the power density reaches ≈2.5 mW cm−2. The high photoresponse primarily arises from the built-in electric fi eld formed at the interface of n-Si and rGO fi lm. The effect of rGO thickness, rGO reduction level, and layout of rGO/n-Si effective contact area on device performance are also systematically investigated.

Full Article：http://onlinelibrary.wiley.com/doi/10.1002/smll.201600835/full