Characterization of Cu₂O thin films prepared by evaporation of CuO powder

Among the potential photovoltaic devices based on semiconductor oxides as active layer is cuprous oxide (Cu₂O). This oxide semiconductor shows many attractive characteristics useful for solar cells production such as low cost, nontoxicity, high mobility and diffusion length of minority carriers, high absorption coefficient and direct energy gap. In this work we report our results of optical and structural investigations of Cu₂O thin films fabricated by thermal vacuum evaporation of CuO powder. The effects of the deposition velocity on structural and optical properties of Cu₂O films were investigated. The X-ray investigations have shown that at low deposition velocity the films consist only of Cu₂O phase without any interstitial phase and have a nano-grain structure. The grains have an average dimensions about (25-30) nm and all these grains showed (200) preferential crystallographic orientation. Optical investigations have shown that the absorption edge of prepared films is due to a direct allowed transition. The value of determined optical band gap is 2.05 eV which corresponds to band gap of bulk Cu₂O.