Hydrothermal growth and characterization of Al-doped ZnO nanorods

Pure and Al doped (0 - 5 at%) ZnO nanorods were prepared by two step hydrothermal method. In the first step, ZnO thin films were deposited on glass substrates by sol-gel spin coat method. In the next step, Al doped ZnO nanorods were grown on the ZnO film coated glass substrates by hydrothermal method using the aqueous solution of [Zn(NO3)2.6H2O] (0.1M), [HMT;C6 H12N4] (0.1M) and [AlCl3.6H2O] prepared using double distilled water. The growth was carried out by maintaining the temperature of the autoclave at 90 °C for 6 h. The structural, morphology and optical properties of the grown ZnO nanostructures were characterized by XRD, FESEM, EDX, UV-Vis and PL spectroscopy. XRD spectra shows both ZnO and Al doped nanorods have the hexagonal wurtzite structure with a strong (002) preferred orientation. As Al doping percentage increases, the XRD spectra show dominance of (101) orientation. The surface morphology of the films were studied using SEM, shows that the both pure and Al doped ZnO films have hexagonal shaped nanorods. The band gap of ZnO nanorods increases with Al doping concentration. The optical parameters such as refractive index, extinction coefficient and dielectric constants were determined using the absorbance and the reflectance data. The PL spectrum shows emission peaks in UV and visible region related to near band emission (NBE) and deep level emission (DLE), respectively. As Al doping increases NBE intensity decreases, this may be due to the doping related defects.