Growth and p-type doping of cuprous oxide thin-films for photovoltaic applications

Cuprous oxide is considered a promising earth-abundant semiconductor material for low-cost photovoltaic applications. In this contribution, we report growth of high-quality Cu₂O crystalline thin-films and p-type doping induced by nitrogen. We present an effective p-type doping method for Cu₂O thin-films by introducing nitrogen gas as a dopant during a reactive sputtering process. Electrical and optical properties of the resulting films are controlled by varying deposition parameters such as nitrogen partial pressure. We successfully reduce the electrical resistivity of the Cu₂O thin-films down to 5.1 Ω·cm and increase hole density to 1.8×10¹⁸ cm^-3. Nitrogen-doped Cu₂O films show higher absorption of low-energy photons while all films exhibit an optical bandgap between 1.9 and 2.0 eV.