Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

Abstract

Graphene (Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes, low costs, and higher performance of their two-dimensional (2D)/three-dimensional (3D) hybrid interfaces in Schottky junction that promotes electron-hole separation. However, due to the built-in potential of Gr/Si as a photodetector, the Iph /Idark ratio is often hindered near zero-bias at relatively low illumination intensity. This is a major drawback in self-powered photodetectors. In this study, we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride (h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the interface. The dark current was able to be suppressed by inserting an h-BN insulator layer, while maintaining the photocurrent with minimal decrease at near zero-bias. As a result, the normalized photocurrent-to-dark ratio (NPDR) is improved more than 104 times. Also, both Iph/Idark ratio and detectivity, increase by more than 104 times at −0.03 V drain voltage. The proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.