Spectroscopic investigations of porous silicon prepared by laser-induced etching of silicon

Abstract

Porous silicon was fabricated by using a Nd:YAG laser in a laser-induced etching process. Scanning electron microscopy was used to monitor changes in surface morphology produced during the etching process. Porous silicon samples were subjected to spectroscopic investigations using an argon-ion laser. The first-order Raman line asymmetry was found to decrease with decrease of the incident argon-ion laser excitation photon energy, while the peak position remained unchanged for a given etching time and power density. The photoluminescence spectra exhibits a red shift in peak position and a dramatic decrease in intensity as the incident photon energy was decreased. Both Raman and photoluminescence data were explained using appropriate quantum confinement models involving two-dimensional confinement and Gaussian size distributions of nanocrystallites constituting porous silicon samples. There is reasonable agreement between the results obtained from Raman and photoluminescence spectroscopic investigations of the PS samples.