In-situ photoluminescence, Raman, and IR spectral study of porous silicon during exposure to thermoelectrons/H atoms, /H₂O and /O₃

Photoluminescence (PL), Raman, and transmission IR spectral measurements of porous silicon (PS) have been carried out during exposure to thermoelectrons and also subsequent exposure to H atoms, H₂O and O₃. The PL band of as-anodized PS was significantly decreased by the first exposure to thermoelectrons accompanied by the intensity reduction of the IR bands due to hydrogenated Si species (Si-H_x; x = 1-3). Upon subsequent exposure to H atoms the PL band intensity was almost recovered but never exceeded its original intensity. This PL recovery was accompanied by re-generation of Si-H_x bonds. In contrast, an overshooting recovery in the PL intensity took place when thermoelectron-treated PS was exposed to H₂O or O₃. The obtained IR spectra showed that Si-O and/or Si-OH bonds were formed at the PS surface. These results demonstrate that the PL of the PS is quite sensitive to the oxygen-included surface bonds.