High-Performance Near-Infrared Photodetector Based on a Graphene/Silicon Microholes Array Heterojunction

This paper reports a heterojunction photodetector constructed from a graphene and silicon microhole array that possesses high-performance near-infrared light detection capabilities. The silicon microhole array constructed by photolithography and reactive ion etching has a smooth surface, which ensures a low surface carrier recombination rate. Meanwhile, the hole-array structure can effectively suppress the reflection of incident light, increase the effective illumination area, and improve the photoabsorption efficiency of the graphene/silicon heterojunction, thereby improving the responsivity of the device. The device exhibits evident current rectification characteristics under a ±3 V bias, with a rectification ratio of 4.30 ×10⁵, and a current on-off ratio of 9.20×10⁵ under irradiation with 810 nm incident light with a power density of 4.25 mW/cm². Under the illumination of 810 nm with the power intensity of 118 μW/cm², the current responsivity of the photodetector can reach 679.70 mA/W, and the specific detectivity is 3.40×10¹² Jones. The voltage responsivity reaches 1.79×10⁶ V/W at an incident power intensity of 7 μW/cm². More importantly, the device exhibited a swift response speed with rise/decay times of 20/21.3 μs. Compared with commercial Si-based photodiodes, the graphene/silicon microhole array photodetector has features, including a simple device geometry and simplified fabrication processes, that may significantly reduce the fabrication cost. The results demonstrate the substantial potential of graphene/silicon microhole array heterojunction photodetectors for low-cost, stable, and efficient near-infrared light detection applications in the future.