P-type transparent conductive CuAlO2 thin films prepared using atmospheric pressure plasma annealing

Transparent conductive CuAlO2 thin films prepared using atmospheric pressure plasma annealing are reported. The sol-gel-derived thin films on the quartz substrate were annealed using atmospheric pressure plasma of N2-10%O2 at 700-800 °C for 10 min. The CuAlO2 phase was obtained at 750 °C. The binding energies of the Cu-2p3/2 and the Al-2p3/2 of the thin films were centered at 932.6 ± 0.2 eV and 73.3 ± 0.2 eV, revealing the valence state of Cu+ and Al3+, respectively. The direct and indirect optical bandgaps of the CuAlO2 thin films were 3.58 eV and 1.81 eV, respectively. Additionally, the CuAlO2 thin films had the conductivity of (1.42 ± 0.1) × 10−3 S/cm with the carrier concentration of (1.32 ± 0.13) × 1014 cm−3. Therefore, atmospheric pressure plasma annealing provides a feasible method for preparing CuAlO2 thin films.