Characterization of aluminium doped zinc oxide nanostructures synthesized by thermal evaporation method

Abstract

This study focuses on the synthesis and characterization of undoped and aluminium (Al) doped ZnO nanostructures for examples nanoflowers, nanorods, nanowires and nanopetals grown by thermal evaporation method. Samples were grown on silicon (100) substrate. The silicon substrate was placed at 17 cm away from zinc target and aluminium powder mixture mounted on horizontal quartz tube under controlled oxygen. The aluminium concentration dependent morphology, crystalline structure and optical properties of these prepared nanostructures were determined. Samples were characterized using field emission scanning electron microscopy, energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and photoluminescence spectroscopy. As the Al dopant concentrations increased, the morphology of ZnO changed from uniform nanoflowers to randomly oriented nanostructures. The flower-like ZnO:Al nanorods have the length of about 333 nm and diameter of about 117 nm. The optimum dopant concentration which can produce uniform size, length and diameter was found to be 0.5 at% of Al. EDX analyses revealed the presence of Zn, O, and Al in the samples. From XRD patterns, the samples had high degree of crystallization with crystallite sizes of about 24.66 nm to 46.98 nm. The ZnO:Al nanoflowers also exhibited a strong ultra-violet emission at 380 nm. Additionally, the band gap energy of ZnO:Al was not significantly changed as found from UV-Vis analyses at 3.24 eV. The concentration of Al plays a significant important role in controlling structural, morphological and optical properties of ZnO nanostructures. The ZnO:Al nanostructures are expected for future technological application due to its impact on optical properties.