Cu-Al-O Transparent Thin Films: Preparation by Spray Pyrolysis Technique and Characterization

Copper Aluminium dioxide CuAlO2 (CAO) thin films have been grown by spray pyrolysis technique on different substrates: glass, zinc oxide and silicon. Different annealing in air at 450-500 degrees C temperature range have been carried out. The thin film structure has been studied from the experimental X-ray diffraction patterns and different morphologies have been found which depend on the substrate type and the grown conditions. The CuAlO2 phase has been found on ZnO substrate after annealing at 500 degrees C in air during two hours. The CuAlO2 grain size was around 30 nm. Optical measurements of a sample on glass substrate after annealing at 500 degrees C have been realized. They have shown a film transmittance around 80% in the visible zone with a band gap near 3.75 eV in a good agreement with literature.