Preparation and characterization of CuAlO2 transparent thin films prepared by chemical solution deposition method

CuAlO2 thin films were prepared on quartz glass and sapphire substrates by chemical solution deposition method using copper acetate monohydrate, aluminum nitrate nonahydrate and 2-methoxyethanol as starting precursor and solvent. The effects of annealing temperature on the structural, morphological, electrical and optical properties have been studied. Via the optimized annealing treatment condition, CuAlO2 film annealed at 850 °C in nitrogen flow of 400sccm under atmosphere pressure exhibits the best performance with the lowest room temperature resistivity of 3.6 × 102 Ω cm and the highest optical transmission in the visible region (>70% at around 600 nm wavelength). CuAl2O4 and CuO phases, not CuAlO2 phase are obtained when annealing temperature is lower than 850 °C. However, a further increase of annealing temperature weakens the crystallization quality and deteriorates the surface morphology of CuAlO2 films as the annealing temperature exceeds 850 °C, leading to an increase in the resistivity and a decrease of the optical transmission in the visible region of CuAlO2 films.