EVIDENCE FOR QUANTUM CONFINEMENT IN POROUS SILICON FROM PHOTOLUMINESCENCE MEASUREMENTS

We have investigated the correlation of photoluminescence (PL) properties 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 relaxation 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 main peak to the blue region were investigated as a function of excitation intensity. On the basis of our results we verified some physical models of porous silicon FL. It is shown that the features of porous silicon PL are associated with a quantum confinement effect in silicon nanocrystallites. A model for competing nonradiative and radiative recombination channels is proposed to explain the observed phenomena.