High optical conversion capability within the interface between graphene and Si under zero bias and visible to near infrared regime

Abstract

In this study, we demonstrate the high performance few-layer graphene-Si sensor with high photoresponsivity of 95 mA/W, operation behaviors with external bias as low as 0 V, and broadband operating light wavelength from 400 nm to 1000 nm by combining high transparency of few-layer graphene and n-type silicon. Although external bias benefits the photoresponsivity, the larger dark current is the price to pay. Under zero bias, the different Si substrate, n-type or p-type, provides variant Schottky barrier height guiding different photoelectrical behavior also be investigated in this work. According to the experimental results, few-layer graphene over p-type silicon (FLG p-Si) has one order higher the dark current of the few-layer graphene over n-type silicon (FLG n-Si) to ensure that the detection region between few-layer graphene and n-type silicon profits high optical-to-electrical conversion. Further, the capability of photocurrent-to-photovoltage conversion directly in one device is also provided and verified to profit the integration proposed device with periphery circuit easily.