Three approaches to surface substance role investigation in porous silicon photoluminescence and its excitation

Photoluminescence (PL) and photoluminescence excitation spectra research, as well as secondary ion mass spectroscopy and infrared vibration spectra measurements, were used for the investigation of PL excitation mechanism of porous silicon. It is shown that there are two types of porous silicon PL excitation spectra: one that consists of visible and ultraviolet bands and one that contains only an ultraviolet one. The different dependencies of intensity of each excitation band upon anodization regimes, as well as ageing and thermal treatment, were observed. Two excitation channels have been shown in porous silicon. The visible PL excitation band at 300 K has been attributed to light absorption of some species on the Si wire surface. The nature of ultraviolet excitation band is also discussed.