Porous samples, which were as-grown films, annealed films, or powders, were studied by using photoluminescence (10 to 700K) and photoluminescence excitation techniques. In addition, absorption measurements were carried out on powder samples. The results were analyzed in terms of current models for the luminescence of porous Si. The conclusion was that, in the case of the present samples, the luminescence was molecular in nature. On the basis of the data, an energy-level diagram which was related to the luminescence was constructed, and the nature of the band structure was considered. It was found that, of all of the models that had been proposed for the photoluminescence of porous Si, the present data were compatible only with a model that was based upon O-related centers.

O.K.Andersen, E.Veje: Physical Review B, 1996, 53[23], 15643-52