Enhanced UV and visible photoluminescence in PS/ZnO composites incorporating Ag and SiO2 dielectric layer

Abstract

Zinc oxide (ZnO), a wide-bandgap semiconductor with excellent optoelectronic properties, suffers from low luminescence efficiency and surface-state-related issues, limiting its practical applications. In this study, we aim to enhance the ultraviolet (UV) and visible photoluminescence performance of ZnO by incorporating Ag nanostructures and a SiO₂ dielectric layer into a porous silicon (PS)-based hybrid structure. Three ZnO-based heterostructures, including PS/Ag/ZnO, PS/SiO₂/ZnO, and PS/Ag/SiO₂/ZnO, were fabricated using electrochemical etching and magnetron sputtering. The structural characterization through X-ray diffraction and scanning electron microscopy revealed that ZnO deposited on PS exhibited low crystallinity and porous island-like growth morphology. The incorporation of Ag and SiO₂ not only improved the adhesion and uniformity of ZnO films but also promoted oriented growth along specific crystallographic directions. Among these heterostructures, the PS/Ag/SiO₂/ZnO configuration demonstrated a 2.5-fold enhancement in UV emission and a 4-fold increase in visible emission, yielding a visible-to-UV intensity ratio of 15.38. These improvements were attributed to the synergistic effects of localized surface plasmon resonance induced by Ag nanoparticles and optical interference within the SiO₂ layer, which enhanced light extraction efficiency and suppressed non-radiative recombination. This work provides a novel structural design strategy for high-performance ZnO-based light-emitting devices, with potential applications in UV/visible sensors, emitters, and photocatalysts.