TRANSIENT PHOTOLUMINESCENCE DECAY IN POROUS SILICON AND SILOXENE

The photoluminescence decay after laser pulse excitation is studied in porous silicon and siloxene as a function of sample temperature, dete ction wavelength, laser intensity, and pulse length. The time dependen ce in all samples is characterized by a nonexponential decay directly after the laser excitation and a single exponential decay for long tim es after the laser pulse. The exponential decay is identical for the p orous silicon samples and annealed siloxene and depends only on detect ion wavelength and sample temperature. As prepared siloxene exhibits t he same decay characteristics. However, the nonexponential decay is mo re pronounced and the single exponential decay is a factor of 2-5 fast er compared with annealed siloxene. The decay of the photoluminescence is another indication of the identical origin of the strong visible l uminescence in porous Si and in annealed siloxene.