COPPER-OXIDE THIN-FILMS GROWN BY PLASMA EVAPORATION METHOD

Copper oxide thin films have been grown by the plasma evaporation method. The thin films were deposited on the substrates by evaporating metallic copper through a plasma discharge in the presence of a constant oxygen pressure. The X-ray diffraction patterns of the films were investigated before and after the films had been annealed in a nitrogen atmosphere. By X-ray diffraction, the cuprous oxide (Cu2O) phase is identified before annealing and it changes to cupric oxide (CuO) after annealing. The optical absorption of the films was also measured. The results were analysed in detail and the band gap energies for Cu2O and CuO are 2.1 eV and 1.85 eV respectively. The types of the film before annealing and after annealing are also measured using thermo-e.m.f. probes and the results indicate that the films are p type. Thin films prepared in the absence of a reactive gas and plasma were also deposited on glass substrates. The X-ray analysis of these films shows the presence of metallic copper only.