High detectivity graphene/si heterostructure photodetector with a single hydrogenated graphene atomic interlayer for passivation and carrier tunneling

Abstract

Hydrogenated graphene is easy to prepare and chemically stable. Besides, hydrogenation of graphene can open the band gap, which is vital for electronic and optoelectronic applications. Graphene/Si photodetector (PD) has been widely studied in imaging, telecommunications, and other fields. The direct contact between graphene and Si can form a Schottky junction. However, it suffers from poor interface state, where the carrier recombination at the interface causes serious leakage current, which in turn leads to a decrease in the detectivity. Hence, in this study, hydrogenated graphene is used as an interfacial layer, which passivates the interface of graphene/Si (Gr/Si) heterostructure. Besides, the single atomic layer thickness of hydrogenated graphene is also crucial for the tunneling transport of charge carriers and its suitable energy band position reduces the recombination of carrier. The fabricated graphene/hydrogenated-graphene/Si (Gr/H–Gr/Si) heterostructure PD showed an extremely low dark current about 10−7 A. As a result, it had low noise current and exhibited a high specific detectivity of ∼2.3 × 1011 Jones at 0 V bias with 532 nm laser illumination. Moreover, the responsivity of the fabricated PD was found to be 0.245 A W−1 at 532 nm illumination with 10 μW power. These promising results show a great potential of hydrogenated graphene to be used as an interface passivation and carrier tunneling layer for the fabrication of high-performance Gr/Si heterostructure PDs.