Self-driven broadband photodetectors on flexible silicon nanowires substrate by forming a heterojunction with reduced graphene oxide

Reduced graphene oxide (rGO), a common two-dimensional material characterized by its modifiable bandgap, has demonstrated outstanding efficacy in the field of broadband photodetection. Typically, the operational efficiency of the as-synthesized silicon nanowires (Si-NWs) based photodetectors is constrained by the scarcity of effective junction areas at the heterojunction interface between rGO and Si-NWs. In order to enhance the interfacial contact area of heterojunctions, a sequential procedure is employed in this work. Initially, a silicon substrate was subjected to metal-assisted chemical etching to create an array of Si-NWs. Subsequently, GO sheets were introduced into the interstitial spaces within the Si-NWs array on one side, and an annealing process was performed subsequently to overlaying an additional layer of GO sheets, resulting in the formation of [Si-NWs/rGO]/rGO heterojunction as the active layer. As the result, our photodetectors Ag/Si-NWs/Si/[Si-NWs/rGO]/rGO/Au demonstrated a notably high specific detectivity of 3.0 × 10¹³ Jones with a responsivity of 0.53 A W^-1 under 1.9 mW cm^-2 980 nm illumination. Furthermore, the underlying physical mechanisms enhancing the device performance of the self-driven broadband photodetectors are discussed.