DEPTH-RESOLVED MICRO-RAMAN STUDY OF POROUS SILICON AT DIFFERENT OXIDATION-STATES

Photoluminescence (PL) and Raman spectra were measured along a cross s ection of porous silicon films at different oxidation times after appl ication of anodic current transients. The average crystallite size was determined from the Raman spectra with the standard phonon confinemen t 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 emiss ion for the outer layers. The crystallite size increases for all layer s, particularly the outer ones. (C) 1997 American Institute of Physics .