The photoluminescence of porous silicon under high hydrostatic pressure - A key experiment to determine the photoluminescence origin

Results on photoluminescence, Raman and X-ray measurements of porous silicon in the pressure range up to 15 GPa are presented. The correlation between these results allows to show that porous silicon photoluminescence still exists in samples which have undergone the Td --> beta-Sn transition. The Raman and X-ray diffraction spectra show that more than 99% of the sample volume has been transformed while the intensity of PL is only reduced by a factor of about 5. This strongly suggests that the photoluminescence of porous silicon does not originate from the Td phase of silicon.