Self‐Powered UV–Near Infrared Photodetector Based on Reduced Graphene Oxide/n‐Si Vertical Heterojunction

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 film and n‐Si. Contacts between the semiconductor layer (rGO, n‐Si) and source–drain Ti/Au electrodes allow efficient 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 10 4 when the power density reaches ≈2.5 mW cm −2 . The high photoresponse primarily arises from the built‐in electric field formed at the interface of n‐Si and rGO film. The effect of rGO thickness, rGO reduction level, and layout of rGO/n‐Si effective contact area on device performance are also systematically investigated.