Plasmonic silicon Schottky photodetectors: The physics behind graphene enhanced internal photoemission

Recent experiments have shown that the plasmonic assisted internal photoemission from a metal tosilicon can besignificantly enhanced by introducing a monolayer of graphene between the two media. This is despite the limitedabsorption in a monolayer of undoped graphene (∼πα=2.3%). Here we propose a physical model where surface plasmon polaritonsenhance the absorption in a single-layer graphene by enhancing the field along the interface. Therelatively long relaxation time in graphene allows for multiple attempts for the carrier to overcome theSchottky barrierand penetrate into the semiconductor. Interface disorder is crucial to overcome the momentummismatch in the internal photoemission process. Our results show that quantum efficiencies inthe range of few tens of percent are obtainable under reasonable experimental assumptions.This insight may pave the way for the implementation of compact, high efficiencysilicon baseddetectors for the telecom range and beyond