Manufacturing of porous silicon; porosity and thickness dependence on electrolyte composition

Porous silicon (PS) layers were manufactured by the anodization of silicon (Si) wafers in hydrofluoric acid/ethanol/water (HF/EtOH/H2O) and hydrofluoric acid/surfactant/water (HF/Decon/H2O) electrolytes. Physical parameters such as thickness (d) and porosity (p) of the formed PS were determined as the function of concentrations of HF, EtOH, Decon ([HF], [EtOH] and [Decon], respectively). It was found that higher [HF] decreases, while higher [EtOH] increases the porosity and helps to produce both uniform anodization and PS layers. The thickness of the formed PS films were measured by profilometry and prooved to be proportional to [HF] and inversly proportional to [EtOH].