Study of synthesis strategies to improve the electrical properties of magnetron sputtered copper oxide thin films

Copper oxides CuO and Cu2O are promising p-type semiconductors for low cost and environmentally friendly solar energy conversion applications. To design optimized devices, a precise control of their optoelectonic properties is necessary. Direct current reactive magnetron sputtering was used to synthesize CuO and Cu2O thin films, and their optoelectronic properties were assessed and compared. It is shown how a heated or biased substrate can modify the electrical properties of sputtered copper oxides. Applying a negative bias mostly increases the hole density and conductivity of the material by one order of magnitude, with a moderate increase of mobility, while heating the substrate (523 K) leads to a clear increase of the hole mobility (up to 0.3 and 4.5 cm2/V s for CuO and Cu2O, respectively) and a decrease of the hole density. A hole density of 1015 cm−3 was reached for Cu2O, while for CuO, it remained as high as 1019 cm−3.