A synergetic enhancement of localized surface plasmon resonance and photo-induced effect for graphene/GaAs photodetector

Abstract

Photodetectors based on graphene/GaAs heterostructure were fabricated and demonstrated for application in self-powered photodetection. Then, Si quantum dots (QDs) were spin-coated onto the surface of the devices to enhance the built-in field by photo-induced doping, because of the tunable Fermi level (EF) of graphene and shallow junction of the heterojunction. Additionally, Au nanoparticles working as a light trapping structure were used to the enhance quantum efficiency of the Si QDs and the optical absorption of the heterojunction, benefitting from localized surface plasmon resonance. Therefore, a large-area photodetector under self-powered conditions achieved a high performance i.e. responsivity (1.81 × 105 V W−1), detectivity (2.0 × 1012 Jones), fast response speed (<0.04 ms), and on–off ratio (6 × 103). The high voltage responsivity opens a promising pathway to ultra-weak light detection, and facilities the development of novel sensors.