EVIDENCE FOR QUANTUM CONFINEMENT IN POROUS SILICON FROM PHOTOLUMINESCENCE MEASUREMENTS

We have investigated the correlation of photoluminescence (PL) propert ies with certain etching conditions, thermal annealing, and powdering of porous silicon. A blueshift of the PL main peak bas observed with a decrease of the PL intensity. PL quenching in p-Si corresponds to a r elaxation or desorption process with the activation energy of 0.37 +/- 0.13 eV. The decrease of the PL efficiency and the shift of the PL ma in peak to the blue region were investigated as a function of excitati on intensity. On the basis of our results we verified some physical mo dels of porous silicon FL. It is shown that the features of porous sil icon PL are associated with a quantum confinement effect in silicon na nocrystallites. A model for competing nonradiative and radiative recom bination channels is proposed to explain the observed phenomena.