Defect study of light-emitting HCl-treated porous silicon

Electrochemically etched porous silicon (PSi) samples have been exposed to a 3 M HCl solution for set time intervals, resulting in a stable and enhanc ed luminescence from this material. These samples were examined using photo luminescence (PL), electron spin resonance (ESR), and Raman spectroscopy. T he Raman chemical disorder component is found to increase significantly wit h increased HCl exposure, tracking also with the increased PL intensity. In contrast, a significant drop in the nanocrystalline Raman component is mon itored, suggesting that the number of silicon nanocrystallites decreases wi th increasing exposure to HC1. ESR spectra of these treated PSi samples ind icate the presence of an NL8 type of oxygen shallow donor, which tracks ext remely well with the increasing PL emission and the amount of chemical diso rder induced with increasing HCl exposure.