ORIGIN OF THE BLUE AND RED PHOTOLUMINESCENCE FROM AGED POROUS SILICON

Two-peak photoluminescence (PL), blue and red, is obtained in the long -time aged porous silicon samples that were initially anodized under A r+ 488 nm laser illumination. Static and dynamic photoluminescence, ph otoluminescence excitation, and Fourier transformation infrared absorp tion and reflection spectra are studied. It is found that the weight o f blue PL increases with increasing the power intensity of the laser u sed during sample preparation. A good monoexponential microsecond deca y over three decades with lifetime of about 5.3 CLS is reported. Infra red spectra are quantitatively studied to reveal the influence of the illuminating laser during anodization on the samples and the relations hip between the oxidation states of the porous silicon and the blue an d/or red photoluminescence. It is suggested that the blue PL in these aged samples comes from the nanometer c-Si core, while the red PL orig inates from the oxide surface.