Hole burning spectroscopy of porous silicon

Abstract

We report on luminescence hole burning experiments that provide a clue for the mechanism of photoluminescence of porous silicon. A large fraction of the light emission is suppressed by an intense resonant pump beam, which introduces an Auger nonradiative recombination. The hole burnt in the luminescence spectrum has two well-defined onsets related to the TO momentum conserving phonons of Si. At low temperatures the hole persists for hours. An increase of the temperature heals the spectral hole, and this is accompanied by a thermoluminescence signal. These results allow us to conclude that most of the luminescence of porous Si arises from radiative recombination between states confined inside the nanocrystals.