Schottky contact analysis of photovoltaic chalcopyrite thin film absorbers

Current–voltage and capacitance–voltage measurements serve to analyze thermally evaporated Al Schottky contacts on Cu(In, Ga)Se2 based photovoltaic thin film devices, either taken as grown or etched in a bromine-methanol solution. The characteristics of the Schottky contacts on the as-grown films give evidence for some dielectric layer developing between the metal and the semiconductor. Etching the semiconductor surface prior to evaporation of the Al front contact yields a pure metal-semiconductor behavior, including effects that can be attributed to an additional diode at the Mo contact. Simulations confirm the experimental results.