Comparative fabrication and performance of metal-semiconductor-metal and heterojunction near-infrared photodetectors using Ag-modified porous silicon

The demand for advanced near-infrared (NIR) photodetectors has surged due to their applications in imaging, communications, and environmental monitoring. This study examines the photoelectric properties of porous silicon (PSi)-based NIR photodetectors modified with silver nanoparticles (AgNPs) in two configurations: metal-semiconductor-metal (MSM) (Au/AgNPs-PSi/Au) and heterojunction (Au/AgNPs-PSi/Si/Al). Device performance was evaluated via current-voltage characteristics under dark and illuminated conditions (850 nm, 20 W/cm²). At 5 V, the heterojunction detector achieved a sensitivity of 20.6 × 10² % and a responsivity of 1.8 mA/W, outperforming the MSM device (3.15 × 10² %, 1.48 mA/W). This enhancement is attributed to the built-in electric field at the junction, which promotes efficient carrier separation, and the optimized AgNP–PSi morphology that enhances light absorption. Additionally, the heterojunction device demonstrated faster rise and fall times, indicating improved carrier transport dynamics. This study provides insight into the design of high-performance NIR photodetectors using modified PSi and highlights the potential of heterojunction configurations for improved photodetection.