Investigation of structural and optical properties of ZnO andMgZnO crystals grown by USCVD

In recent years, the studies on oxide-based materials have been gained importance. Zinc oxide (ZnO) has become an important semiconductor material due to its wide bandgap (3.37 eV) and a large exciton binding energy (~60 meV). Because of these unique properties of ZnO, it is started to enhance new growth/preparing methods. One of the new growth methods is Ultrasonic Spray Chemical Vapor Deposition (USCVD) which is convenstional CVD enhanced with liquid precursor delivery. In this thesis, the growth behavior, structural, electrical, and optical properties of ZnO and Magnesium Zinc oxide (MgZnO) grown by USCVD are investigated. The effect of some physical and chemical parameters such as different growth temperatures, precursor molarity, ultraonic transducer power, usage of different substrates, annealing process on the growth properties of ZnO and MgZnO crystals. For high crystal quality and lower surface roughness, the optimum growth temperature for ZnO crystals is determined to be 350 °C. As well as the polycrystalline structure of ZnO, the growth direction of grown ZnO crystals is dominant in (0002) direction and also other peaks related to the wurtzite phase of ZnO are shown. In grown MgZnO crystal growth, though Mg content in the precursor is kept as constant depending on different growth temperatures, Mg mole fraction in MgZnO crystals is found to be different from initial Mg content. Also, according to obtained results initial Mg content and Mg mole fractions in grown MgZnO crystals did not same but there is a linear relation between them. Growth behavior of ZnO and MgZnO crystals are mostly hexagonal and triangular shaped with two dimensional nanoplatelets and three dimensional islands. As a result of ZnO and MgZnO growths, the optimum growth conditions for high quality crystals have been determined.