The formation of the low-dimensional porous silicon-based structures with extremely high exciton binding energy

The model of pore formation in silicon during electrochemical etching is presented. The model takes into account the transport of reagent and by-products of Si dissolution inside the pores. This enables to model the evolution of morphology of the porous layer through all its thickness as well as to explain the appearance of a number of experimentally observed effects. The exciton characteristics of Si nanosized structures with exciton-phonon coupling factor far exceeding the unity are investigated by the method, based on the Froelich-Hopfield relation and analysis of the photoluminescence spectra, measured at a single temperature. The obtained values of exciton binding energy in Si nanocrystallites agree with published data obtained in other approaches. The simple method of size estimation of Si crystallites is proposed on the basis of the described technique for the exciton parameter determination. (C) 2002 Elsevier Science B.V. All rights reserved.