Abstract
Visible light emission from porous silicon (PS) has been investigated in-situ with photoluminescence (PL), Raman, and transmission IR spectroscopies in an ultra-high vacuum. The PL intensity of as-anodized PS was significantly decreased by the first exposure to thermoelectrons accompanied by the intensity reduction of the IR absorption bands due to hydrogenated Si species (Si-Hx; x=1-3). Upon subsequent exposure to H atoms the lost PL intensity was almost recovered but never exceeded its original intensity. This PL recovery was accompanied by regeneration of the Si-Hx bonds. In contrast, an exceeding recovery was observed for the thermoelectron-treated PS after exposure to H2O or O3. Simultaneous IR measurements revealed that Si-OH or Si-O bonds were formed at the PS surface. These results demonstrate that the PL of the PS is closely related to the oxygen-included surface chemical bonds.
