Kinetics of luminescence in porous silicon: A fluctuation approach

The kinetics of photoluminescence due to tunneling radiative recombination of photoexcited electrons and holes localized at a crystallite-matrix interface is theoretically treated within the framework of a model concept according to which the structure of porous silicon is treated as a random set of nanometer-sized silicon crystallites embedded into the SiO2 matrix. The developed theory predicts a relatively slow (stretched exponential) decay of photoluminescence intensity that results from averaging of the intensity in each of the photoluminescence events over the mutual arrangement of electrons and holes (localized on the surface of a particular crystallite) and over the crystallite sizes. The proposed approach provides an adequate quantitative description of low-temperature experimental data on the photoluminescence kinetics at a fixed radiant energy and the time evolution of the photoluminescence spectra of porous silicon. (C) 2001 MAIK "Nauka/Interperiodica".