Influence of dispersive exciton motion on the recombination dynamics in porous silicon

Abstract

An extended photoluminescence (PL) study of porous silicon is presented. Different PL techniques have been used: continuous wave excited (cw) PL, selectively excited PL, excitation spectroscopy of the PL, time decay of the PL, and time resolved PL. These measurements have been performed on a set of samples of various porosities and at various temperatures. Strong experimental evidence is found for the influence of disorder and of dispersive motion of excitons on the recombination dynamics. The data are interpreted in the framework of the trap-controlled hopping mechanism for the dispersive motion of excitons in a disordered array of Si nanocrystals.