Porous silicon (por-Si) is prepared by the electrochemical etching of single-crystal n-silicon in an aqueous–alcoholic solution of hydrofluoric acid in the presence of hydrogen peroxide oxidizer. The dependence of the high-frequency C–V characteristics of Al/por-Si/Si heterostructures on the relative humidity is studied. A model of capacitor structure is proposed, and a method of analyzing its capacitance as a function of the water vapor partial pressure in terms of the adsorption isotherm is elaborated. Within the framework of this model, the porosity of the material, the effective fraction of silicon dioxide in the por-Si, the fraction of intercommunicating porosity, the micropore-to-mesopore volume ratio, and the mesopore size distribution are determined. The porous silicon prepared in this work seems promising as a sensitive layer in capacitance-type humidity sensors.
展开▼
