Ultrabroadband Silicon-Based Infrared Detectors by Integrating with Multilayer Graphene

Silicon-based photodetectors are dominant in modern imaging due to their CMOS compatibility and cost-effectiveness, yet their spectral range is fundamentally limited by the material's bandgap, precluding infrared detection. Although graphene-silicon heterojunctions offer a promising route to extend the response range, single-layer graphene (SLG) suffers from weak absorption, and conventionally stacked multilayer graphene (MLG) introduces interfacial contamination and charge traps that degrade performance. Herein, we demonstrate an MLG-silicon heterostructure, in which the MLG is synthesized by chemical vapor deposition (CVD) and integrated with silicon using a synergistic etching methodology. A defect-minimized heterojunction interface with exceptional cleanliness is fabricated, enabling both enhanced optical absorption and efficient collection of photogenerated carriers. The resulting devices demonstrate an excellent photoresponse across the 635 nm to 8 μm range, with rise and fall times of 6 and 5.7 μs, respectively. This work provides a foundation for next-generation broadband infrared detection chips and supports the scalable manufacturing of advanced silicon-based optoelectronic systems.