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

Uriel Levy,N. Asger Mortensen,P. A. D. Gonçalves,Meir Grajower,Jacob B. Khurgin

doi:10.1063/1.4973537

Abstract

Recent experiments have shown that the plasmonic assisted internal photoemission from a metal to silicon can be significantly enhanced by introducing a monolayer of graphene between the two media. This is despite the limited absorption in a monolayer of undoped graphene (∼πα=2.3%). Here we propose a physical model where surface plasmon polaritons enhance the absorption in a single-layer graphene by enhancing the field along the interface. The relatively long relaxation time in graphene allows for multiple attempts for the carrier to overcome the Schottky barrier and penetrate into the semiconductor. Interface disorder is crucial to overcome the momentum mismatch in the internal photoemission process. Our results show that quantum efficiencies in the range of few tens of percent are obtainable under reasonable experimental assumptions. This insight may pave the way for the implementation of compact, high efficiency silicon based detectors for the telecom range and beyond.

Highlights

In recent years, plasmonic enhanced silicon detectors based on internal photoemission (IPE) across the metal-silicon Schottky barrier have been demonstrated and shown to be useful in the detection of telecom band (1300-1600 nm)—beyond the detection capability of conventional silicon photodiodes and photoconductors
While a large variety of photodetectors based on two dimensional materials have been demonstrated,[16] most of them are based on mechanisms which are different from the internal photoemission effect and to date, the graphene-metal-silicon photodetector seems to be a leading candidate for CMOS compatible internal photoemission detection in the telecom window
The observed enhancement in quantum efficiency makes photodetectors based on internal photoemission highly relevant for a variety of applications, e.g., chip scale optical communications

Summary

Introduction

Plasmonic enhanced silicon detectors based on internal photoemission (IPE) across the metal-silicon Schottky barrier have been demonstrated and shown to be useful in the detection of telecom band (1300-1600 nm)—beyond the detection capability of conventional silicon photodiodes and photoconductors. Assigning a transmission probability T to the transition from graphene to either silicon or metal, the effective emission time becomes τem = τrt/(2T ).

Results

Conclusion