Microwave Synthesis of Aluminium Doped ZnO Nanostructures and Characterization

Nanocrystalline Al doped ZnO (AZO) nanostructures have been synthesized by a simple surfactant free thermal decomposition method in a microwave oven. Zinc nitrate hexa hydrate and ethylene glycol were used as the precursor materials to prepare ZnO and aluminum nitrate was added for Aluminium doping (1 to 7%). The samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UVvisible spectroscopy (UV), Photoluminescence (PL), Energy Dispersive X-Ray Spectroscopy (EDX) and Impedance Spectroscopy (IS). Analyses show that the Al doping significantly affected the crystalline nature, particle size, optical properties and conductivity of the processed ZnO nanoparticles. The XRD spectra indicate that the ZnO crystal has a hexagonal wurtzite structure. TEM images show the lattice arrangement of atoms in hexagonal shapes. The optical properties of the samples are investigated by measuring the UV-VIS absorption at room temperature. There was a variation in particle size in the range of 20nm to 52nm, with incorporation of dopant. Also, the band gap seemed to be influenced by dopant concentration, with a high value of 3.202eV for 5% doping. A tenfold increase of conductivity (0.302 to 3.75 (m Ω cm) -1) results with Al doping. 1 Madras Christian College, East Tambaram, Chennai 600059, India. 2 currently @ Elmhurst College, 190 Prospect Ave, Elmhurst, Illinois 60126, USA. *Corresponding author