Properties of ZnO thin films grown at room temperature by using ionized cluster beam deposition

ZnO films with a thickness of 120 nm were deposited on Si(100) at room temperature by using the reactive-ionized cluster beam deposition technique. The effects of the acceleration voltage (V_a) on the properties, such as the crystallinity, the induced film strain, the surface roughness, and the electrical and the optical properties of the films, were investigated. The ZnO films had only a (002) crystalline orientation and uniformly composed through the whole thickness. As the V_a increasesd, more strain was induced in the film, and the packing density caused by the structural imperfection was lowered. The films prepared under the optimum condition (V_a = 3 kV) on a glass substrate showed good optical transmittance, and the band-gap of the film was evaluated to be 3.32 eV.