Capacitance-Voltage Technique for the Determination of Carrier Concentrations in Thin Film Photoanodes

The metal/insulator semiconductor capacitance-voltage technique is seen as advantageous for obtaining semiconductor carrier concentrations for thin-film photoanodes. It makes it possible to measure semiconductor properties in a way that does not depend on the electrolyte. It is noted that the properties of thin-film SiO2 insulators are well known, and that interactions between the semiconductor and the insulator are less complex and better understood than those of a liquid junction. The C-V method can also offer self-consistency. At positive bias, for example, the capacitance appropriate to the insulator film thickness is obtained. What is more, the capacitance-voltage data can be analyzed according to specified equations in order to calculate two independent values of carrier concentration; these serve as an internal check on the experimental technique.