Electrochemical Methoxylation of an HF-Etched Porous Silicon Surface

The electrochemical methoxylation of a porous silicon (PS) surface using an anhydrous methanol etch and the resulting modification of the photoluminescent emission (PL) from the surface are evaluated within the framework of the silanone-based silicon oxyhydride fluorophors and their methylated counterparts. The molecular electronic structure of the ground-state singlet and low-lying triplet electronic states of some 20 oxyhydrides of the form O Si(R) 2, O Si(R)OR, and O Si(OR) 2, where R = H, CH 3, or SiH 3, is considered. The predicted electronic transitions correlate well with the experimentally observed PL for PS and its methoxylated counterpart. The substitution of a methyl (CH 3 ) group for a silyl (SiH 3 ) unit is predicted to produce the observed PL blue shift accompanied by an increased PL intensity and stability.