X-RAY EXCITED OPTICAL LUMINESCENCE (XEOL) STUDY OF POROUS SILICON

It has been postulated that light emission from porous silicon is caus ed by quantum confinement of the electron states within silicon wires formed by anodic electroetching of silicon. In order to investigate th is hypothesis we have made measurements of the X-ray excited optical l uminescence (XEOL) and the total electron yield (TEY) as a function of X-ray energy for porous silicon at station 3.4 of the SRS at Daresbur y laboratory. Results have shown that the luminescence is associated w ith elemental silicon, and this is true for as prepared and oxidised m aterial. In the latter case the XEOL spectrum is completely different from the TEY. However, by considering the microscopic origin of the ex citation together with time-dependent relaxation data, we conclude tha t the emission comes from silicon surface states and not quantum effec ts in the nanoparticles. This is in contrast to other similar studies.