Preparation of intrinsic and Al-doped ZnO thin layers by Spray pyrolysis

Intrinsic and Al doped zinc oxide thin films at different concentration ranging 1 to 5 at % were prepared by Spray pyrolysis onto glass substrates at low substrate temperature (300 °C). The structural, electrical and optical properties of ZnO:Al films were investigated. The X-ray diffraction and Raman patterns show that ZnO:Al films have a hexagonal wurtzite structure with a preferential orientation in the <002> direction. The lowest resistivity was found for ZnO films doped with 3 % aluminum. Optical characterization shows that ZnO films exhibit high optical transmittance above 85% in the visible wavelength range. Increasing Al content in ZnO thin films leads to an increase of the band gap energy from 3.27 to 3.38eV.