Strong photoinduced increase in the luminescence intensity of anodically oxidized porous silicon

A strong nonlinear intensification of photoluminescence upon application of low-power (<1 W/cm(2)) cw laser excitation (488 nm) at room temperature in a freshly prepared, anodically oxidized porous silicon (AOPS) was detected. The maximum absolute photoluminescence intensity and its maximum relative change as a function of the irradiation time were attained in layers of porous silicon with the average degree of oxidation. As a result of laser illumination, the intensities of the O-3-SiH, Si-O-Si, and Si-OH vibrational modes were higher than the intensity of the SiHn modes in the infrared absorption spectra. The results confirmed that the structure of the oxide on the surface of the silicon crystallites and the structure of Si/SiO2 interface play an important role in the photoluminescence process. (C) 1996 American Institute of Physics.