Spectroscopic investigation of porous silicon prepared by laser-induced etching

Porous silicon was prepared by using an argon-ion laser in a laser-induced etching process with different etching time. Scanning electron microscopy was used to monitor changes in surface morphology produced during the etching process. Porous silicon samples were subjected to spectroscopic investigations. The first-order Raman line asymmetry was found to decrease with increase of the etching time, while the peak position downshifted for a given power density. The photoluminescence spectra (PL) exhibit a blue shift in peak position with etching time. Both Raman and PL data were explained using appropriate quantum confinement models involving three-dimensional confinement and Gaussian size distributions of nanocrystallites constituting porous silicon samples. There is reasonable agreement between the results obtained from Raman and PL spectroscopic investigations of the PS samples.