Multilayer-stacked Ag/MgO/CdS@AgO on porous silicon scaffold for efficient photodetectors

This work develops an efficient multilayer photodetector by incorporating silver nanoparticles (Ag-NPs) into a CdS/MgO heterostructure deposited on a porous silicon (PS) scaffold. CdS-NPs were synthesized via laser ablation in liquid, while MgO-NPs and Ag-NPs were prepared through a simple chemical route. PS was obtained using a photoelectrochemical etching technique, offering a high surface area and excellent carrier transport pathways. The morphological, structural and optical properties of the materials were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), UV–Vis spectroscopy and photoluminescence (PL) analysis. A series of multilayer photodetector devices were fabricated with varying ratios of Ag-NPs to CdS (1:1, 1:3 and 3:1) using the drop-casting deposition method to optimize the nanocomposite interface. All the prepared samples were evaluated as photodetectors in the visible spectrum under the same measurement conditions. Electrical and optical evaluations revealed that the device based on the Ag/MgO/CdS@AgO/PS/Si/Ag architecture with a 3:1 CdS/Ag-NPs ratio exhibited the highest photoresponse, which recorded the highest detector value of [Formula: see text] Jones, a quantum efficiency of nearly 91%, and a responsivity of up to 0.53[Formula: see text]A/W at 780[Formula: see text]nm. Meanwhile, the Ag/MgO/AgO/PS/Si/Ag device showed the lowest performance, highlighting the synergistic effect of CdS and AgO-NPs in boosting light harvesting and charge transfer. In contrast, MgO particles were used as a light-transmitting layer due to their wide energy gap ([Formula: see text]5.1[Formula: see text]eV), which affords them high transparency in the visible spectrum and an effective barrier function that improves device stability and reduces surface recombination. These results demonstrate a promising pathway toward efficient, silicon-compatible photodetectors for optoelectronics.