A Study on the Morphology of the Silver Nanoparticles Deposited on the n-Type Porous Silicon Prepared Under Different Illumination Types

In this study, the influence of n-type porous Si (n-PS) morphology properties and the performance of Ag nanoparticles (AgNPs)/n-PS Raman substrate were investigated. Two kinds of n-PS morphology (macro n-PS and mud n-PS) structures were fabricated by laser-assisted etching (LAE) process and ordinary light-assisted etching (OLAE) process, respectively. A simple and cost-effective immersion plating process of n-PS in 0.01 M concentration of AgNO3 for 16-min immersion time was used to synthesize AgNPs. The morphological properties of the deposited AgNPs on the macro n-PS layer showed that the deposition process is concentrated on the pore wall with a little density, while for mud n-PS, the AgNP layer is mainly composed of high-density uniformly distributed spherical particles located over the mud surface. Surface-enhanced Raman scattering (SERS) process of AgNPs/n-PS revealed strong dependence on the morphology and the density of AgNPs. Enhancement factor (EF) of Raman signal of AgNPs/mud n-PS substrate is three orders of magnitude higher than that of AgNPs/macro n-PS substrate of about 1.6 x 10(11) and 8.2 x 10(8), respectively.