Mechanism of luminescence from porous silicon

A strong nonlinear increase in the photoluminescence intensity under laser excitation at room temperature is found for porous silicon obtained by anodic oxidation. It is shown that the maximum photoluminescence intensity correspond to samples of anodically oxidized porous silicon in the intermediate oxidation state. Laser excitation is found to increase the intensity of vibrational modes in the O-3 - SiH, Si-O-Si and Si-O-H configurations with respect to the Si-Hn mode intensity in IR absorption spectra. It is experimentally confirmed that the oxide structure on the surface of silicon crystallites and the structure of the Si/SiO2 interface determine to a great extent the photoluminescent characteristics.