Depth-resolved micro-Raman study of porous silicon at different oxidation states


Photoluminescence ~PL! and Raman spectra were measured along a cross section of porous silicon films at different oxidation times after application of anodic current transients. The average crystallite size was determined from the Raman spectra with the standard phonon confinement model. Before oxidation, the PL emission energy and crystallite size were found to be independent of the layer depth. Also, the integrated PL emission was larger for the middle layers. The effect of oxidation was a blueshift of the PL band and a decrease in the integrated emission for the outer layers. The crystallite size increases for all layers, particularly the outer ones.

Appl. Phys. Lett. 71, 2166 (1997)