Research About Al-doped ZnO Films Prepared By Pulse-modulated RF Magnetron Sputtering

Transparent conducting oxide (TCO) film is a kind of optoelectronic thin film which iswidely used. Among the TCO films, the process of In-doped SnO2(ITO) films is advanced, andhas been widely used in industrial applications. The aluminum-doped zinc oxide (AZO) film isa kind of transparent conductive oxide film with low resistivity and high transmittance, Becauseof abundant materials, non-toxic, easily-etched, it has been given widely research anddevelopment. But the research of AZO thin films focuses on the influence of differentprocessing conditions like substrate temperature, or the difference between direct-current sourceand RF source. There is no other innovative source been used in magnetron sputtering.Therefore, in this work, AZO thin films were deposited on ordinary glass by the continuous RFmagnetron sputtering, the pulse-modulated RF magnetron sputtering and a target of AZO using98%wt ZnO added2%wt Al2O3. Thin films were measured by UV-visible spectrophotometer,four-point probe and X-ray diffraction, respectively.1. AZO films were deposited by RF sputtering on glass substrates, different processingconditions on the optical and electrical properties were discussed in detail. Optimal conditionsobtained by experiment was substrate temperature300℃, working pressure0.35Pa, sputteringpower200W, target substrate distance60mm and sputtering time30min. Under the optimalconditions the result was the transmittance84.3%, the sheet resistance23/□.2. AZO films were deposited by pulse-modulated RF magnetron sputtering with theselected optimal conditions in the above experiment. The influence of duty cycle was discussedin detail by setting two control groups which were the same sputtering time and the samethickness of the film.(1) In the same sputtering time (30min), the films deposited by60%duty cycle had thebest optical and electrical properties, the sheet resistance is17/□, the transmittance is84.1%.(2) Thinking of the influence of different thickness, according to the consistency of theaverage deposition rate, different films with thickness between500~600nm were deposited bylengthened sputtering time. In this group, films deposited by40%duty pulse had the bestoptical and electrical properties. At last, optimal conditions obtained by experiment wassubstrate temperature300℃, working pressure0.35Pa, peak sputtering power200W, targetsubstrate distance60mm. Under the optimal conditions the result was the transmittance85%,the sheet resistance14/□.The method of pulse-modulated RF provided a new method for the magnetron sputteringprocess. Compared with ordinary RF magnetron sputtering, this method modulates the rate ofdeposition and enhances the properties of thin films. At the same time, because of the higher charged particle density in the same average power, the method of pulse-modulated RF don’tneed high substrate temperature, the range of substrate materials is expanded.