The Magnetron Sputtering Deposition And Investigation Of ZnO:Al Transparent Conductive Thin Film

In this paper ZnO:Al transparent conductive fims were deposited on glass substrate by using DC magnetron sputtering technique. The effects of substrate temperature, sputtering power and annealing atmosphere on the film structure, optical and electrical properties have been studied systemically, and the mechanisms of electrical property are discussed. In addition, in order to realize high quanity ZnO:Al films deposition at low temperature, H-doping and ZnO:Al target, Zn target co-sputtering methods are applied to grow ZnO:Al films, the influence of H2 flows, the power on Zn target and substrate temperature on ZnO:Al films properties were investigated in details separately. The main results obtained as follows:(1) ZnO:Al thin films have been deposited on glass substrate applying ZnO:Al ceramic target by DC magnetron sputtering. All the ZnO:Al films with the preferential orientation of (002) plane are polycrystalline and possess hexagonal wurtzite structure with their crystallographic c-axis perpendicular to the substrate. The grain size of the films is between 18-32 nm.(2) Substrate temperature, sputtering power and annealing atmosphere have great influences on structure, optical and electrical properties of ZnO:Al films. The crystalline quality of ZnO:Al film is best when the film was prepared under 120 W of sputtering power and 400℃of substrate temperature. All the films show good transmittance during the visible region. Resistivity decrease with the increasing of substrate temperature; the resistivity drops to the lowest, when the film was prepared at 500℃; after annealing in vacuum and Ar, the resistivity drop, but after annealing in O2, N2 and air, the resistivity rise.(3) To realize high quanity ZnO:Al films deposition at low temperature, The effects of H2 flows in the sputtering atmosphere on the properties of ZnO:Al films are studied. As the H2 flow incresing, grain size decreases, carrier concentration increases and resistivity drops. The transmittance of ZnO:Al films is above 90% from 400-900 nm, indicating excellent optical property.(4) The influence of power on Zn target and substrate temperature on the properties of ZnO:Al films is studied by using ZnO:Al target, Zn target co-sputtering. With the increasing of the power on Zn target, the content of Zn element rise and the crystalline distance increases, which may be result of the the increasement of the concentration of Zn interstitial, carrier concentration goes up and resistivity drops correspondingly. With the increasing of substrate temperature, the structure, transmittance and resistivity have been improved.