CARRIER RECOMBINATION IN POROUS SILICON

Photoluminescence properties of porous silicon have been studied as a function of the synthesis conditions, the temperature, and the ambient medium. The results are interpreted in terms of a modification of the electron spectrum due to a quantum size effect and a competition betw een radiative and radiationless recombination in nanostructures of the porous silicon. The relative weight of the recombination channels cha nges in the direction of the radiationless recombination with increasi ng characteristic dimensions of the clusters in the porous layer. This effect is manifested in experimentally observable changes in the lumi nescence intensity and spectrum. This luminescence is a superposition of the emission from silicon structures of various sizes.