MONOEXPONENTIAL MICROSECOND DECAY OF BLUE PHOTOLUMINESCENCE IN AGED POROUS SILICON PREPARED WITH AR+ 488 NM

Blue photoluminescence is observed in aged porous silicon samples anod ized under Ar+ 488 nm laser illumination. No samples have been undergo ne any heating treatment process. Both nanosecond and microsecond deca y of blue photoluminescence have been measured. Samples show a good mo noexponential microsecond decay with lifetimes of about 5.3 ps. Photol uminescence excitation spectra of blue and red Photoluminescence indic ate there is a large Stokes shift (about 800-900 meV) in the excitatio n spectra of red photoluminescence while no this marked Stokes shift i n that of blue photoluminescence. The possible origin of the photolumi nescence is discussed based on the experimental results.