Effect of annealing process on structural and optical properties of Au-doped thin films (NiO:WO₃) fabricated by PLD technique

In this research the films (NiO:WO₃) prepared onto glass substrates and doping with different content of gold (0, 0.03, 0.05, 0.07) by PLD technique (Nd:YAG laser beam) the wavelength of this laser is 1064 nm, the average frequency of the pulses is 6 Hz, and the pulse duration is 10 ns, energy 600 mJ and number of shots 400 with thickness measured by interference method is about 200 ± 5 nm. The films annealing to temperature 300˚C for 1h. X-ray diffraction showed that after annealing at 300°C, the crystal size increased to the (200) plane and the quality of the film improved. From atomic force microscope (AFM), after annealing the films to 300 °C increase in the values of RMS and the average grain size values which compared with the values before the annealing process. UV–Vis spectrophotometer has been used to study optical measurements within the range of wavelength from 400 nm to1100 nm. The energy gap value shifted from 2.3 to 2.85 eV and increase after annealing the sample. Finally the optical constants k, n, εr and εi, were also calculated and analyzed.