Instability of the photoluminescence of porous silicon

Results of studies of the photoluminescence of porous silicon with differen t prehistories have revealed the mechanism and nature of the instability of the luminescence properties of freshly prepared samples. It was establishe d that the initial quenching and subsequent rise of the photoluminescence i s attributable to the intermediate formation of silicon monoxide (photolumi nescence degradation) and subsequent additional oxidation to form SiO2 (pho toluminescence rise). Ultraviolet laser irradiation accelerates this proces s by a factor of 200-250 compared with passive storage of the samples in ai r. Plasma-chemical treatment in an oxygen environment merely results in a s ubsequent rise in the photoluminescence as a result of the formation of mon oxide on the porous silicon surface. A kinetic model is proposed for this p rocess. (C) 1999 American Institute of Physics. [S1063-7842(99)02906-2].