Visible and near-infrared dual-band photodetector based on gold–silicon metamaterial

Abstract

A photodetector with a controllable response spectrum and high responsivity shows great potential in practical photoelectric applications. Here, we design and experimentally demonstrate a visible and near-infrared (NIR) dual-band photodetector by integrating the out-of-plane Au gratings and n+-Si groove substrate metamaterial (ASGM). Simulation, experimental, and calculation results indicate that the absorption spectrum can be tailored by surface plasmon resonances (SPRs) of different interfaces and Si-groove resonance. Visible-light absorption is caused by Si-groove resonance, SPRs of the Au–air interface, and high-frequency mode SPRs of the Au–Si interface. NIR absorption is induced by the SPRs of the Au–Si interface. Moreover, out-of-plane coupling between upper and lower Au gratings gives rise to an enhanced electric field and broadened SPR absorption. The respective photoresponsivity in the visible and NIR band is more than 7 and 3 mA/W without an external bias, with a maximum responsivity of 13 mA/W at 535 nm. The photoresponse of such ASGM-based dual-band photodetectors can be modulated so that they may be used in various fields like medical imaging, optical communication, and aerography.