FAST AND SLOW VISIBLE LUMINESCENCE BANDS OF OXIDIZED POROUS SI

The visible luminescence of porous Si is known to contain at least two spectrally distinct emission bands with widely different response tim es. The orange-red luminescence component (1.5-1.9 eV) decays in times being of the order of 10 mu s at room temperature. The blue-green ban d (2.3-2.6 eV) is very much faster with response time in the 10-ns ran ge. It is shown that with increasing degree of oxidation the fraction of the fast luminescence intensity rises from similar to 1% of the tot al in the as-prepared porous Si to become the dominant spectral compon ent in strongly oxidized material. For the rapid-thermal-oxidized mate rial excited with 337-nm radiation, the intensity of the fast luminesc ence is comparable to that in the as-prepared state.