Design of Resonant Cavity-Enhanced Schottky Graphene/Silicon Photodetectors at 1550 nm

In this work, a new concept of resonant cavity-enhanced graphene/silicon Schottky photodetector operating at 1550 nm is theoretically investigated. Device is essentially a Fabry-Perot interferometer where two high-reflectivity distributed Bragg reflectors surround an optical cavity composed of hydrogenated amorphous silicon, graphene, and crystalline silicon. The enhancement of the optical field inside the cavity allows greatly increasing the single-layer graphene optical absorption whose behavior is described by the derivation of a closed analytical formula. The optoelectric transduction mechanism is based on the internal photoemission effect through the crystalline silicon/graphene Schottky junction. It has been shown that in a properly designed device, a graphene optical absorption, external quantum efficiency, and responsivity of 100%, 35%, and 0.43 A/W can be obtained, respectively. Finally, device bandwidth and noise, in terms of dark current and normalized photocurrent-to-dark current ratio, have been discussed. The insights included in this work can open the path for the investigation of a new family of high-performance photodetectors that can find application in silicon photonics.