Fluctuation theory of photoluminescence of porous silicon

A theory of photoluminescence (PL) kinetics of porous silicon (PS) is developed. In this theory, the approach suggested by the authors earlier is extended to the case of finite temperatures. The theory is based on the concept of electron-hole recombination, which occurs in structural units of PS both through the tunneling mechanism (playing a role even for T = 0 K) and through thermally activated diffusion of photoexcited carriers. The PL kinetics is analyzed in terms of two models considered in the literature, in which PS is treated as a random ensemble of spherical nanocrystallites or quantum wires. The results are applied to interpret experimental data on the kinetics and instantaneous PL spectra of PS. Although both models basically provide an adequate quantitative description of the experimental data at both low and room temperatures, the model of spherical nanocrystallites seems preferable. (C) 2004 MAIK "Nauka / Interperiodica".