ELECTROCHEMICAL METHOXYLATION OF POROUS SILICON SURFACE

An electrochemical process aiming at the grafting of methoxy groups on the hydrogenated porous silicon surface at room temperature has been designed. This takes place through partial anodic dissolution of porou s silicon in anhydrous methanol. A dissolution mechanism is proposed b y analogy with that of the anodic dissolution of silicon in aqueous fl uoride media. The methoxylated surface exhibits improved optical chara cteristics (increased photoluminescence efficiency, blue shift of the emission), similar to porous silicon anodically oxidized in a nonfluor ide aqueous electrolyte. Its stability against aging is also improved as compared to that of the hydrogenated surface, but without reaching the stability of anodically oxidized porous silicon. This residual sen sitivity to aging is ascribed to the nonnegligible amount of SiH speci es which remains on the methoxylated surface upon the modification pro cess.