Synergistic absorption enhancement via silicon nanowires array wrapped with reduced graphene oxide for long-wave infrared, room-temperature self-driven photodetectors

As a novel two-dimensional material, graphene has brought new opportunities for long-wave infrared (LWIR) photodetectors due to its unique optoelectronic, mechanical, chemical and thermal properties. Conventional planar graphene structures exhibit limited light absorption capabilities due to their inherent two-dimensional configuration. In this work, a self-driven LWIR photodetector Ag/[Si-NWs/rGO]/rGO/Au based on a novel hybrid architecture by integrating reduced graphene oxide (rGO) into the gaps of a silicon nanowires (Si-NWs) array to construct a three-dimensional light-trapping structure, is presented. Such a kind of innovative design significantly expands the photon absorption pathway in both lateral and vertical dimensions to enhance the photogenerated carriers’ extraction efficiency under LWIR light illumination. A remarkable specific detectivity (D*) of 1.59×10¹⁰ and 5.02×10⁹ Jones under 25 mW/cm² 11.5 and 14 µm illuminations, respectively, is obtained from photodetector Ag/[Si-NWs/rGO]/rGO/Au under zero-bias at room temperature, showing a significant breakthrough in achieving ultrahigh responsivity for LWIR detection at room-temperature. Further, the underlying mechanism behind the enhanced performance is explored in detail.