Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector
graphene, hexagonal boron nitride, van der Waals heterostructure, self-powered
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.
Tsinghua University Press
Ui Yeon Won, Boo Heung Lee, Young Rae Kim, Won Tae Kang, Ilmin Lee, Ji Eun Kim, Young Hee Lee, Woo Jong Yu. Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector. Nano Research 2021, 14(6): 1967-1972.