Effect of electron irradiation on the electronic structure and photoluminescence behavior of porous silicon

The effect of electron irradiation on the electronic structure, surface com position, and photoluminescence behavior of porous n-type Si was studied. T he density of states in the valence band determined as a function of irradi ation dose by Auger electron spectroscopy indicates that 4-keV electron irr adiation leads to decomposition and rapid desorption of the hydrogen-contai ning species present on the quantum-wire surface. As the irradiation dose r ises, radiation-induced defects gradually accumulate, and the amorphous con tent of porous Si increases. Irradiation of porous Si at temperatures from 20 to 125 degrees C allowed us to determine the apparent activation energy of irradiation-induced photoluminescence quenching, Delta E = 0.13 eV. It i s shown that the photoluminescence quenching is mainly due to the formation of nonradiative-recombination centers during hydrogen desorption. A model for the outdiffusion of desorption products from porous Si is presented, an d the hydrogen diffusivity in porous Si is estimated.