Role of oxygen flow rate on the structural and optical properties of copper oxide thin films grown by reactive magnetron sputtering

Copper oxide thin films were grown by DC reactive magnetron sputtering. The structural investigation of the sputtered films was carried out using X-ray diffraction. The surface morphology of the films was observed through atomic force microscopy. A crossover in the crystalline phase from cuprous to cupric oxide (tenorite) was observed as a result of variation in the oxygen flow rate during sputtering. Deposition rate was also found to be a function of the oxygen flow rate, and it was found that the deposition rate decreased with an increase in the oxygen flow rate which could be attributed to the possible target oxidation at higher oxygen flow rates. Variation of grain size of the films with oxygen flow rate was analyzed through AFM analysis. Dependence of oxygen flow rate on the formation of two phases of copper oxide was also confirmed through the optical band gap measurements.