Nanostructured Gold Interlayer-Enhanced Self-Powered Photodetectors for Visible and Long-Wave Infrared Dual-Band Applications

Abstract

Self-powered dual-functional detectors comprising a p-Si/nanostructured Au/CdS sandwiched structure, which respond to the visible and long-wave infrared dual-band, are developed for visible light communication and passive human recognition without Fresnel lenses. Various configurations of nanostructured Au interlayers are fabricated via solid-state dewetting, significantly enhancing the optoelectronic and pyroelectric properties of the original p-Si/CdS system. The p-Si/Au nanoparticles/CdS detector achieves a responsivity of 0.47 A/W, a response time of 830 ns, a −3 dB bandwidth of 0.33 MHz, and human recognition distance of up to 2 m. The improvement in optoelectronic properties is attributed to enhanced light absorption resulting from multiple internal reflections and localized surface plasmon resonance, as well as an enhanced built-in electric field within the Au/CdS Schottky junction. The improvement in pyroelectric properties is related to enhanced polarization of CdS resulting from the interface polar symmetry, which not only improves the visible photoresponse at high pulsed light frequencies but also enables effective detection of human radiation. Additionally, the effects of body parts, vertical distance, and moving velocity on pyroelectric human recognition are systematically investigated. This work expands the diversity of multifunctional photodetectors with great potential for visible and long-wave infrared dual-band applications.