Study of deposition modes of Cu<sub>2</sub>O films by RF magnetron sputtering for application in solar cell structures

The deposition of Cu2O films was carried out by radio-frequency (RF) magnetron sputtering in an oxygen-free environment at room temperature. The effect of the power and pressure in the chamber on the deposition rate, structural and optical properties of Cu2O films was studied. It was shown that the dependence of the Cu2O film deposition rate on the sputtering power is almost linear and increases slightly with increasing argon pressure in the chamber. It was found that all Cu2O films have a predominantly nanocrystalline structure consisting of columnar grains, the average size of which increases from 10 to 30 nm with an increase in the sputtering power from 25 to 100 W and in the chamber pressure from 3·10–3 to 7·10–3 mbar. At the same time, the Cu2O films have a relatively smooth surface with an average roughness in the range from 4.5 to 5.9 nm. It has been established that the optimal sputtering power for deposition of Cu2O films with the largest grain size and low surface roughness is 75 W and chamber pressure of 5·10–3 mbar. It has been shown that under this magnetron sputtering mode, the Cu2O film has two main diffraction peaks, which correspond to the orientations of the crystal planes (111) and (200) for the cubic Cu2O phase, as well as high optical absorption of up to about 600 nm and a band gap of 2.18 eV. The models of solar cells based on the ZnO/Cu2O heterojunction were manufactured by magnetron sputtering at room temperature and their current-voltage characteristics were studied. The obtained results can be used in the development of structures and technological processes for the formation of solar cells on glass and flexible substrates using the magnetron sputtering method.