Sol-Gel Method Synthesis and Characterization of Mn doped ZnO Semiconductor Nanostructures for Optoelectronic Devices

Abstract

The purpose of this thesis is to study the growth mechanism and optimize the parameters of this method for Optoelectronic devices and to investigate the structure, optical and electrical properties of Mn doped ZnO semiconductor nanostructures in detail by means of X-ray diffraction (XRD) and Ultra violet-visible absorbance spectrophotometer (UV-Vis). Furthermore, a possible synthesis mechanism for undoped and Mn doped ZnO semiconductor nanostructures in solution was proposed and the effect of Mn doping in different concentrations on the morphology, optical and electrical properties of ZnO nanostructures were systematical studied. The effect of Mn doping on optical quality of ZnO nanostructures was also carefully examined. These nanostructures were successfully synthesized by sol-gel method using the chemicals such as zinc acetate hexa-hydrate, manganese (II) chloride hexa hydrate, ammonia solution, citric acid, poly ethyl glycol and distilled water without further purification. The X-ray powder diffraction (XRD) of the samples was characterized by using SHIMADZU XRD 7000 X-ray diffract meter using the principle of Bragg Brentano Geometry, with Cu-Kα radiation. XRD confirmed that all the synthesized undoped ZnO and Mn doped ZnO nanostructures were crystalline in the wurtzite structure; and the average sizes of the samples were investigated, which conform nanostructures’ formation. Additional peaks were also observed for Mn doped ZnO nanostructures in this study. UV-Vis absorption spectra were recorded by using a UV-Vis spectrophotometer in the photon wavelength range between 300 and 800 nm. From the optical study, the absorbance in UV regions was increased with the increasing Mn doping concentration. For Mn doped Zn nanostructures, the spectra of U-V show a blue shift in energy band. It was found that the doping of ions have a significant influence on the optical properties of ZnO nanostructures.Analyzing the results of various types of characterizations, it has been assessed that Mn doped ZnO nanostructures were successfully synthesized.