Luminescence properties of ambient air aged and thermally oxidized porous silicon

The photoluminescence (PL) properties of ambient air aged porous silicon (PS) and thermally oxidized PS have been studied at various temperatures. Furthermore, the decay dynamics, and stability characteristics (as a function of laser irradiation time) have been measured, and X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) have been carried out. Both ambient air aged and thermally oxidized PS show blue and green luminescence, but the luminescent properties of these samples are quite different from each other. Specifically, the constant PL peak position and abnormal PL intensity variations with decreasing temperatures are detected for ambient air aged PS. However, a substantial continuous blue shift and an increase of PL intensity with decreasing temperatures are observed for thermally oxidized PS. These different observations are attributed to differences in the structural configurations of the samples. (C) 1999 Elsevier Science S.A. All rights reserved.