Experimental investigation on structural and optical properties of ZnO: AZO nano particles by hydrothermal synthesis

The undoped and Al-doped ZnO (AZO) nanostructures were synthesized by using simple hydrothermal process with two different pH values 6 and 10. The structural and optical properties of the ZnO and 0.5 % AZO nano particles were investigated using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscope, atomic force microscope, X-ray diffraction (XRD), Ultraviolet–visible (UV) spectroscopy and photoluminescence (PL). It is observed from XRD results; on aluminium doping the crystalline size reduces significantly. It can be clearly seen from the FESEM images that Al doping causes the crystalline structure of ZnO to agglomerated small grain nano particles and TEM confirms that the particles are of nanometer size. The UV absorption indicates that blue shift of the samples increases the optical band gap, and decreases the average crystallite size. In the PL spectra, undoped ZnO exhibit an excitonic peak in the UV region and a defect-related peak in the visible region, whereas Al doping leads to a suppression of c lattice parameter and blue shift of luminescence with blue and green emission.