Thin, free-standing Cu2O substrates via thermal oxidation for photovoltaic devices

Cu₂O 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 Cu₂O substrates with thicknesses of less than 20 microns which may be handled and processed into devices. Development of thinner Cu₂O substrates is essential as extrinsic doping has been impossible thus far, and intrinsic Cu₂O is highly resistive. Hall measurements indicate that the substrates had Hall mobilities of 10-20 cm²V^-1s^-1 and carrier concentrations on the order of 10¹⁴ cm^-3. Current-voltage characteristics of these Cu₂O substrates were derived from liquid junction Schottky barrier device measurements which indicate open circuit voltages of Voc ~ 600 mV.