Sputtered cuprous oxide thin films and nitrogen doping by ion implantation

The structural, optical and electrical properties of sputtered cuprous oxide thin films have been optimized through post-deposition thermal treatments. Moreover we have studied the effects of nitrogen doping introduced by ion implantation followed by the optimized oxidant thermal annealing. Three concentrations have been used, 0.6 N%, 1.2 N%, and 2.5 N%. Along with the preservation of the CuO phase, a slight optical band gap narrowing and a significant conductivity enhancement has been observed with respect to the undoped samples. These results can be justified by the absence of further oxygen vacancies promoted by dopant introduction and by the substitution of O atoms by N ones. This lattice configuration has been guaranteed by the post implantation annealing in oxidant atmosphere. The used doping technique represents an original out-of-equilibrium approach toward the formation of low-resistivity contacts on CuO films for photovoltaic applications.