Effect of Water Vapor on the Growth of Textured ZnO-Based Films for Solar Cells by DC-Magnetron Sputtering

Large-grain zinc oxide (ZnO) films have been deposited on glass substrates by DC magnetron sputtering in H 2 O-Ar mixtures at elevated substrate temperatures. The (002)-oriented columnar structure grown in pure Ar changed into the granular structure as the partial pressure of water vapor increased. Low-resistivity pyramidal textured ZnO:Al films were sputter-deposited in a mixture of H 2 O-Ar(1:1) at 300-400°C. The 2-µm-thick films possessed a sheet resistance of 9 Ω/□ and optical transmission of 80% at 550 nm after annealing in a vacuum. These films have considerable potential as window materials for solar cells.