G. Dalba et al., Evidence of x-ray absorption-edge shift as a function of luminescence wavelength in porous silicon, PHYS REV B, 62(15), 2000, pp. 9911-9914
X-ray absorption fine structure (XAFS) at the Si K edge in porous silicon h
as been measured by monitoring the photoluminescence yield (PLY) in differe
nt parts of the luminescence band: at increasing luminescence energy, a con
tinuous positive shift of the x-ray absorption edge has been observed. The
peculiar selectivity of the partial PLY-XAFS technique to the luminescent s
ites allows us to perform a size selection of the different nanostructures
distributed in a single porous-silicon sample. The recombination of carrier
s localized in quantum confined nanocrystals is confirmed to be the main ca
use of the optical emission.