DYNAMICS OF THE DEGRADATION BY PHOTOOXIDATION OF POROUS SILICON - FTPL AND FTIR ABSORPTION STUDY

Fourier transform photoluminescence (FTPL) and Fourier transform infrared (FTIR) spectroscopy have been performed in situ during etching and on freshly anodized porous silicon after etching. During etching we find a continuous increase of Si-H bonds and no additional oxygen species at the inner surface of porous silicon. Other recent work has shown that freshly etched microporous silicon in oxygen ambient is subject to aging by oxidation. We demonstrate that photoirradiation in oxygen ambient causes photo-oxidation at the inner surface and thus accelerates aging significantly. Furthermore, we investigate the influence of different ambients and varying laser power on the dynamic process of PL degradation of, and increasing oxygen incorporation into, freshly etched porous silicon. We observe a rapidly decreasing PL intensity accompanied by PL peak blue shifts up to 200 meV.