Localized photo-assisted electro-deposition of zinc selenide into p-type porous silicon

Electroplating of II-VI semiconductors like ZnSe into porous silicon can be an efficient and low cost method to fill the porous volume with a transpar ent and conductive material. With n-type porous layers, ZnSe impregnation i s more effective near the sample surface because of reaction rate limitatio ns due to diffusion in the electrolyte. In this paper, it is shown that the deposition of ZnSe into p-type porous silicon can be localized in the lowe r part of the porous layer if the reduction reaction rate is monitored by l imiting the charge carrier supply. This can be done by controlling the powe r of the laser beam which photo-generates the carriers at the bottom of the pores. Studying the porous layer chemical composition by Auger electron sp ectroscopy confirms that the deposit is localized at the pore bottom, where as the changes in the chemical composition of the porous silicon surface ar e analyzed by infra-red spectroscopy.