SIMULTANEOUS MICROPHOTOLUMINESCENCE AND MICRO-RAMAN SCATTERING IN POROUS SILICON

Light-emitting porous silicon (PS) layers prepared by anodic oxidation on p-substrates have been studied by micro-Raman scattering and micro photoluminescence spectroscopy simultaneously. A complementary study b y transmission electron microscopy has been made. A change in microsco pic structure with depth is observed as well as a red shift of the lum inescence as the focalized laser beam approaches the bulk substrate. T his result pointed out a correlation between the structural depth inho mogeneity and optical properties of porous silicon in agreement with q uantum size effects.