Structural, electrical and optical properties of ZnO thin films deposited by sol–gel method

Thin films of intrinsic and Al-doped ZnO were prepared by the sol–gel technique associated with spin coating onto glass substrates. Zinc acetate dehydrate, ethanol and monoethanolamine were used as a starting material, solvent and stabiliser, respectively. Structural, electrical and optical characterizations of the films have been carried out. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The four-points technique was used to characterize thin films electrically. All films exhibit a transmittance above 80–90% along the visible range up to 650 nm and a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge 3.3 eV. Intense UV photoluminescence is observed for undoped and 1% Al-doped ZnO films.