Significant Enhancement in the Conductivity of Al-Doped Zinc Oxide thin Films for TCO Application

Abstract

Nanostructured Al-doped Zinc oxide (ZnO) thin films were deposited on glass substrate by chemical bath deposition (CBD) using aqueous zinc nitrate solution and subjected for different characterizations. Effect of Al[Formula: see text] substitution on the properties of ZnO annealed at 400[Formula: see text]C was studied by XRD and UV-Vis for structural studies, SEM and TEM for surface morphology and DC four probe resistivity measurements for electrical properties. Al[Formula: see text] substitution does not influence the morphology and well-known peaks related to wurtzite structure of ZnO. Electron microscopy (SEM and TEM) confirms rod shaped Al-doped ZnO nanocrystals with average width of 50[Formula: see text]nm. The optical band gap determined by UV–Visible spectroscopy was found to be in the range 3.37[Formula: see text]eV to 3.44[Formula: see text]eV. An EPR spectrum of AZO reveals peak at [Formula: see text] is due to shallow donors Zn interstitial. The DC electrical resistivity measurements of Al-doped ZnO show a minimum resistivity of [Formula: see text]-cm. Therefore, these samples have potential use in n-type window layer in optoelectronic devices, organic solar cells, photonic crystals, photo-detectors, light emitting diodes (LEDs), gas sensors and chemical sensors.