Structural and morphological evolution of ZnO cluster film prepared by the ultrasonic irradiation assisted solution route

Through the novel ultrasonic irradiation assisted solution route similar to successive ionic layer adsorption and reaction method, nanocluster ZnO layer with high preferential orientation along (002) plane and the porous feature was deposited on glass substrate. Variations of crystalline structure and morphology of the obtained layer with the deposition cycle were investigated. The formation mechanism of the porous structure and the function of ultrasonic irradiation were preliminarily discussed. Results show that, the deposition of ZnO layer follows not the layerwise growth mode, but the simple crystal growth and accumulation mode. With the increase of the deposition cycle, the quantity of deposited ZnO particles and the particle coverage ratio increase significantly, the strong preferential orientation along (002) plane reserves, and the mean size of ZnO crystallites decreases slightly. The ultrasonic irradiation has been justified to possess two major functions, to enhance the preferential orientation along the c-axis, and to modify the size and shape of ZnO crystallites.