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

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 Al3+ substitution on the properties of ZnO annealed at 400 degrees 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. Al3+ 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 nm. The optical band gap determined by UV-Visible spectroscopy was found to be in the range 3.37 eV to 3.44 eV. An EPR spectrum of AZO reveals peak at g = 1.96 is due to shallow donors Zn interstitial. The DC electrical resistivity measurements of Al-doped ZnO show a minimum resistivity of 3: 77 x 10(-2) Omega-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.