Perturbation of the luminescent silicon emission by adsorbed dyes

Fluorescent dyes have been used to impregnate partially oxidized porous silicon produced by stain etching. The properties of the structures produced have been studied by photoluminescence (PL) and IR spectroscopies before and after extensive solvent extraction of the dye. PL spectra from extracted wafers are different from nonextracted ones and show, most of the time, three peaks. One peak at 700 nm is assigned to luminescent silicon before the dye impregnation; a second emission peak resembles the dye luminescence from solution, and a third peak at 630–670 nm is attributed to silicon emission perturbed by the adsorbed dye. A model is proposed to account for this new peak, by including band splitting due to the adsorption of the dye molecules.