PHOTOLUMINESCENCE OF SM DOPED POROUS SILICON - EVIDENCE FOR LIGHT-EMISSION THROUGH LUMINESCENCE-CENTERS IN SIO2 LAYERS

After oxidation promoted by gamma-ray irradiation, in the photolumines cence (PL) spectra of Sm doped porous silicon (PS), there are three sh arp peaks, superimposed on a broad band, with wavelengths near to thos e of the Sm doped SiO2 [R. Morimo, T. Mizushima, and H. Okumura, J. El ectrochem. Soc. 137, 2340 (1990)]. The experimental results indicate t hat Sm-related luminescence centers can be created within the oxide of porous silicon, and only in porous silicon with high porosity can the Sm-related luminescence be found in the SiO2 layer. This experimental result can be explained by the fact that the excitation of electron-h ole pairs occurs in nanoscale silicon, and the recombination occurs at the Sm-related luminescence centers in SiO2 layers covering nanoscale silicon.