High and Fast Response of a Graphene-Silicon Photodetector Coupled with 2D Fractal Platinum Nanoparticles

2D material-based electronic devices like graphene-silicon photodetectors (Gr-Si PDs) have attracted much attention of researchers in the past few years. Due to the nature of Schottky junction, Gr-Si PDs have ultrafast response. However, responsivity of Gr-Si PDs is very low, which hinders their practical application. Low work function of Gr and poor absorbance of Si are mainly responsible for this problem. Here, a novel approach for coupling of Gr-Si PDs with 2D fractal platinum nanoparticles (Pt NPs) is demonstrated to enhance the responsivity and speed up the response of Gr-Si PDs at the same time. 2D morphology of fractal Pt NPs helps to overcome the coffee-ring effect. Fully covered fractal Pt NPs remarkably improve the absorption of Gr-Si PDs by plasmonic effect. Responsivity of Gr-Si PDs thus is remarkably enhanced to 26 A W-1. Meanwhile, work function of Gr is improved by the physical doping of high-work-function Pt NPs. Therefore, the Schottky barrier of Gr-Si junction is increased, resulting in faster response. Improvement in the built-in electric field reduces the background noise of Gr-Si PDs as well. These results indicate toward a simple and novel approach for fabricating high and fast response Gr-Si PDs.