Tunable responsivity in high-performance SiC/graphene UV photodetectors through interfacial quantum states by bias regulation

Abstract

Graphene/SiC/graphene photodetectors were fabricated by epitaxial graphene prepared on semi-insulated 4H-SiC (0001) using the ultra-high vacuum high-temperature thermal decomposition method. The device exhibits a maximum responsivity of 0.01 A/W, a 103 UV–visible rejection ratio, and a high detectivity of 1.34 × 1012 Jones with a ultra-low saturation dark current of 3 × 10−13 A. Interfacial quantum states were adopted at graphene/4H-SiC heterojunction for tuning the Schottky barrier by reverse bias. The extracted Schottky barrier heights decrease from 0.91 to 0.81 eV with bias due to the upward shift of the charge-doped graphene's Fermi level. The peak responsivity of the detector is tuned from 260 to 300 nm, which indicates SiC photogenerated carriers are released from the interfacial quantum states by applied bias. More carriers transit over the Schottky barrier so that the photodetectors achieve high photoelectric conversion.