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

Cu
₂
O 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
₂
O substrates with thicknesses of less than 20 microns which may be handled and processed into devices. Development of thinner Cu
₂
O substrates is essential as extrinsic doping has been impossible thus far, and intrinsic Cu
₂
O is highly resistive. Hall measurements indicate that the substrates had Hall mobilities of 10-20 cm
²
V
^-1
s
^-1
and carrier concentrations on the order of 10
¹⁴
cm
^-3
. Current-voltage characteristics of these Cu
₂
O substrates were derived from liquid junction Schottky barrier device measurements which indicate open circuit voltages of Voc ~ 600 mV.