The growth of the silver nanoparticles on the mesoporous silicon and macroporous silicon: A comparative study

Abstract

Two porous silicon (PS) layers, namely mesoPS and macroPS have been prepared by electrochemical etching (ECE) and photo–electrochemical etching (PECE) processes, respectively. The surface morphology of mesoPS and macroPS reflects a different form of morphology. Silver nanoparticles (AgNPAs) have been obtained through immersion of PS samples in AgNO₃ solution. The mechanism of Ag growth depends on the substrate morphology. In the case of using mesoPS substrate, the AgNPAs have sizes ranging from 0.25 to 2.25 µm, so they can’t enter inside pores and therefore they aggregate on the mesoPS surface, while by using macroPS substrate, they have sizes ranging from 0.1 to 1.5 µm, decorate the inner of the pores and the separate Ag nanoaggregates form on the macroPS surface. The highest SERS has been obtained for AgNPAs/macroPS substrate rather than AgNPAs/mesoPS substrate. The enhancement factor (EF) values achieved by using AgNPAs deposited on macroPS and mesoPS substrates are about (1.8×10⁶) and (3.2×10⁴), respectively.