Thin, free-standing Cu_2O substrates via thermal oxidation for photovoltaic devices

Cu_2O is a promising, earth-abundant alternative to traditional photovoltaic materials (CIGS, CdTe, etc.) because of its low cost, high availability, and straightforward processing. We report a method to fabricate Cu_2O substrates with thicknesses of less than 20 microns which may be handled and processed into devices. Development of thinner Cu_2O substrates is essential as extrinsic doping has been impossible thus far, and intrinsic Cu_2O is highly resistive. Hall measurements indicate that the substrates had Hall mobilities of 10–20 cm^2V^(−1)s^(−1) and carrier concentrations on the order of 10^(14) cm^(−3). Current-voltage characteristics of these Cu_2O substrates were derived from liquid junction Schottky barrier device measurements which indicate open circuit voltages of Voc ∼ 600 mV