BLUE-LIGHT EMISSION FROM RAPID-THERMAL-OXIDIZED POROUS SILICON

We have converted the hydrogen-passivated surface of porous Si prepare d by electrochemical etching into a stable oxidized one using a rapid thermal oxidation process. At a high oxidation temperature (T-ox) abov e about 800 degrees C, blue photoluminescence (PL) with a peak wavelen gth of about 400 nm was clearly observed. On the other hand, at low T- ox below about 800 degrees C, the PL peak remained at about 750 nm, wh ich is similar to that of as-anodized porous Si. From Fourier transfor m infrared (ETIR) spectra, are found that the PL spectra are closely r elated to the structure of the oxygen-terminated surface on Si nanocry stallites. Spectroscopic data suggest that the red PL and the blue PL originate from a surface state and a quantum-confinement state, respec tively.