Facile synthesis of ZnO films with anisotropic preferred orientations: An effective strategy for controllable surface and optical property

Although one-dimensional ZnO nanodevices have already been widely used in practical applications, there still exists limitation of inevitable growth along polar orientation for wurtzite ZnO. Herein, ZnO films grown along diverse preferred orientations including the non-polar, semi-polar and polar directions could be acquired by a facile and reproducible low-temperature aqueous solution deposition method. The non-epitaxial growth pattern was realized by introducing moderate amount of sodium citrate and ammonia into the non-polar solution without any surfactant or passivated agent. Preferential growth mechanism and surface properties of as-prepared anisotropic ZnO films were investigated. Transmission spectra of ZnO films with anisotropic preferred orientations exhibited an isotropic transmittance. Visible emission spectra indicated multifarious defect types and quantities related to diverse preferred orientations of anisotropic ZnO films. This work could not merely enrich the crystallographic growth of ZnO films along anisotropic orientations, but also benefit for designing ZnO film-based nanodevices with desirable performances from the perspective of regulating anisotropic growth of ZnO.