CHEMICAL MODIFICATION OF THE PHOTOLUMINESCENCE QUENCHING OF POROUS SILICON

The photoluminescence of porous silicon can be quenched by adsorbates, and the degree of quenching can be tuned by chemical derivatization o f the porous silicon surface. Thus, as-prepared porous silicon has a h ydrophobic, hydrogen-terminated surface, and the photoluminescence is strongly quenched by ethanol and weakly quenched by water. Mild chemic al oxidation (iodine followed by hydrolysis) produces a hydrophilic po rous silicon surface. Photoluminescence from this hydrophilic material is quenched to a lesser extent by ethanol and to a greater extent by water, relative to the original surface. This demonstrates that the vi sible luminescence from porous silicon is highly surface-sensitive, an d the surface interactions can be tuned by specific chemical transform ations.