Synthesis of Silver@Gold (Core@Shell) Nanoparticles Deposited on Porous Silicon for Enhanced Spectral Responsivity

This study investigates the impact of laser pulse energy (500 mJ/pulse) on silver, gold, and silver@gold NPs and deposited on porous silicon. The objective is to assess their effects on structural, optical, morphological, and electrical properties, aiming to identify optimal conditions. Nanoparticles are produced through the technique of pulsed laser ablation in liquid (PLAL). This involves employing a Q-switched Nd: YAG laser operating at a wavelength of 1064 nm and pulse duration of 10 ns. X-ray diffraction (XRD) analysis validates the crystalline development of (core–shell) NPs, evident from the presence of XRD peaks corresponding to Au and Ag NPs. Morphological analysis reveals excellent adhesion between NPs and the substrate (PS), enhancing structural stability. UV–vis spectra demonstrate a localized surface plasmon resonance (LSPR) band within the 420–540 nm range. This band shifts from two peaks to one with increased gold content. A comparison of the photoluminescence emission spectra of porous silicon and Ag@Au NPS/PS at room temperature. The porous silicon exhibits an extreme PL emission band broadening centered at a visible wavelength of 620 nm (2.033 eV), which reveals the excellent quality of the PS structure. Photodetector measurements highlight maximum responsivity for the Ag@Au/PS photodetector. These Ag@Au NPs show promising attributes for high-performance photodetector applications.