Influence of solution resistivity and post-anodizing treatments of PS films on the electrical and optical properties of metal/PS/Si photodiodes

An experimental study of the influence of solution resistivity and the effect of post-anodizing treatments of PS films on the electrical and optical properties of the metal/PS/Si photodiodes was performed. Porous silicon (PS) samples were made from p-Si in ethylene-glycol/HF or ethanol/HF solutions of different concentrations. The anodized sample was left in the dark for different times in the HF/base electrolyte in which the porous layer had been fabricated or in methanol. The results show a strong influence of the etching solution parameters and PS surface post-treatments on kinetic changes of the deviceʹs electrical properties. The mechanism of electrical conduction was interpreted in terms of charge carrier transport through shallow traps associated with the surface impurities.