2 SOURCES OF EXCITATION OF PHOTOLUMINESCENCE OF POROUS SILICON

The change occurring in the photoluminescence spectra and the photolum inescence excitation spectra during aging of porous-silicon samples in air and in vacuum has been investigated. It was found that the charac ter of the photoluminescence changes occurring during aging depends on the wavelength of the exciting light: In the case of excitation in th e visible-range band of the luminescence excitation spectrum (lambda(e xc) > 490 nm) the photoluminescence decreases and in the case of excit ation in the ultraviolet band it predominantly increases. It is shown that the two bands of the luminescence excitation spectrum (visible an d ultraviolet) correspond to two different objects on the surface of t he porous layer. (C) 1997 American Institute of Physics.