Stability in photoluminescence of porous silicon

The effect of aging on photoluminescence (PL) of porous silicon has been st udied for different storage media with a view to find suitable conditions f or stabilizing the PL spectra. IR studies have been performed on both initi ally oxidized and oxide-free porous silicon samples to get an insight of th e possible chemical changes in the porous layer after treating it in a numb er of environments. The changes in the PL spectra, both blue shift and red shift in appropriate environments, are ascribed to growth in Si=O bonds lea ding to trapped electron states at the Si/SiO2 interface in conformity with the recently proposed model [M.V. Wolkin et al., Phys. Rev. Lett. 82 (1999 ) 197]. In addition, a mechanism and a theoretical model for oxidation of s ilicon nanocrystallites in porous silicon have been proposed to explain the observed experimental results. An excellent agreement between the observed rate of shift of PL peak wavelength with storage time and that calculated from the proposed model has been found. Possibility of stabilizing the PL i ntensity and peak wavelength by keeping it in a non-oxidizing environment a nd to tune the PL peak wavelength with different storage media have also be en discussed. (C) 2000 Elsevier Science B.V. All rights reserved.