Effect of annealing on the morphology and the optical characterization of the AZO:Co thin film prepared by Sol–Gel process

Abstract

In this work, the ZnO thin film, the Al-doped ZnO (AZO) thin film (0.98M ZnO, 0.02M Al) and the (Al,Co) co-doped ZnO thin film (AZO:Co) (0.95M ZnO, 0.02M Al, 0.03M Co) were deposited on the glass substrate by the Sol–Gel method. We fabricated a sample of the ZnO thin film, a sample of the AZO thin film and three samples of AZO:Co thin films. The spin-coating was used to deposit thin film on the glass substrate. The ZnO and the AZO thin films were annealed at 450[Formula: see text]C while three samples of the AZO:Co thin films were annealed at 300[Formula: see text]C, 450[Formula: see text]C and 600[Formula: see text]C in air for 60 min, respectively. In order to prepare three samples of the AZO:Co thin films, we deposited the (Al,Co) co-doped ZnO on the glass substrate for 20 s then all samples were per-heated at 80[Formula: see text]C for 10 min. we repeated this deposition process five times for each sample. Finally, three samples were annealed at 300[Formula: see text]C, 450[Formula: see text]C and 600[Formula: see text]C in air for 60 min, respectively. The procedure to prepare of the ZnO and AZO thin films was like the AZO:Co thin films except that the annealing temperature was 450[Formula: see text]C. The structural and optical properties of the thin films were investigated by X-ray diffraction technique, UV-Vis spectrophotometer and Field Emission Scanning Electron Microscopy (FESEM). Results indicated that (Al,Co) co-doping in the ZnO thin film improve the optical transmission while changes in the lattice structure is small with respect to the AZO thin film. Also, the AZO:Co thin film which was annealed at 450[Formula: see text]C exhibited simultaneously the high thickness and high optical transmission.