Radical-assisted magnetron sputtering ZnO: Al transparent conductive thin film research

　　Title: Radical-assisted magnetron sputtering ZnO: Al transparent conductive thin film research
　　Author: Wu Bingjun
　　Degree awarded: China University of Science and Technology
　　Keywords: ZnO;; AZO;; magnetron sputtering;; resistivity;; carrier concentration;; mobility;; optical transmittance;; oxygen ion bombardment;; into effect;; anti-sputtering effect;; spatial distribution;; oxygen interstitial defects;; annealing;; impurity scattering
　　Abstract:
　　Solar cells, flat panel display and touch screen technologies such as the emergence and rapid development of transparent conductive oxide thin films made more and more and more high demand. ZnO: Al (referred to as AZO) transparent conductive Rare earth magnets film because of its excellent optical properties of, a rich source of cheap raw materials and environmentally friendly, etc. caused widespread concern in the industry, is considered to replace the In203: Sn (referred to as ITO) transparent conductive film materials, the best candidate. AZO film with the thin-film solar cells in the practical and indium as ITO film raw material supply and demand gap is increasing, AZO film is entering industrial production stage.
　　This article uses AZO ceramic target, metal target of zinc, aluminum and zinc alloy target and other targets in Japan Shincron target company's RAS-1100C large radical-assisted magnetron sputtering device sputtering Zn0 and AZO thin films to study the film electrical, optical, micro-structure, stress, band gap, refractive index and other physical properties change with the sputtering parameters; for AZO ceramic target sputtering target during sputter deposition in front of the fixed substrate resistivity of AZO films and many other physical properties of the phenomenon of uneven spatial distribution appeared to start a systematic study and found that the sputtering process produces high-energy oxygen ion bombardment into effect is to make the physical properties of AZO thin films appear uneven spatial distribution of the root causes; for metal target the complexity of the process of sputtering a metal target sputtering zinc zinc oxide film microstructure during the film morphology and crystallinity with the sputtering power and oxygen flow rate of the oxidation zone change, and comparative study of the sputtering area high-energy oxygen ion bombardment caused by the anti-sputtering phenomenon; the same time with this film is also in the air and hydrogen atmosphere annealing results in a variety of defects in the film state were discussed, trying to reveal the state of film in a variety of defects on the film properties impact, so as sputtering performance more excellent foundation for AZO thin films.
　　Through comparative experimental study, this paper has been following conclusions and results:
　　l, AZO ceramic target by the sputtering parameters on the optimization of the RAS has been deposited on the drum resistance rate 2.4 × 10-3Ω · cm, carrier concentration of 2.49 × 1020 cm-3, the migration rate 10.5cm2V-ls- 1,550 nm wavelength transmittance of 85% of the sample of AZO thin films;
　　2, observed at a fixed target different regions of the substrate before the deposition of AZO thin films on the resistivity, carrier concentration, mobility and http://www.chinamagnets.biz/ many other physical properties of the spatial distribution of apparent phenomena; target sputter deposition of the channel in front resistivity of AZO thin films up to 2.2 × 10-2Ω · cm, while the two intermediate non-target sputter deposition area in front of the resistivity of AZO thin films can be as low as 4.9 × 10-4Ω · cm, a difference of up to 45 times so.
　　3, by XPS, XRD characterization of such high energy oxygen ion bombardment that is the target into effect before the uneven spatial distribution of resistivity of the source. Oxygen ions from the sputtering process of lattice oxygen precipitation in the form of negative ions in the target negative voltage electric field to accelerate the high energy bombardment obtained above to the substrate, resulting in films of grain damage and inhibition of film along the (0002) highly oriented growth direction and the introduction of a large number of oxygen in the film interstitial defects. Large amounts of oxygen interstitial defects in the free-electron capture film carrier, and cause lattice distortion, increase the film in the neutral impurity scattering, which led to film carrier concentration and mobility decrease, resistivity increased.
　　4, RAS drum film deposited on the performance of the regional deposition of thin films, the average performance results. Sputtering parameters influence mainly through the bombardment of oxygen ions into the effects of the strength of the crystallization conditions, and film quality and impact of the drum on the preparation of AZO Thin Films.
　　5, through the RAS target sputtering of zinc oxide thin films of zinc in the process of forward and reverse deposited films of zinc oxide thin film study observe the morphology and crystalline state of evolution with the degree of oxidation, has been with the film microstructure sputtering power and oxygen oxidation zone of the phase diagram of velocity distribution, analysis of RAS typical metal target sputtering process of the physical process of sputtering the district, with excellent performance for the sputtering of crystalline AZO transparent conductive film provides a physical basis.
　　6, comparative study of various metal sputtering target sputtering process caused by oxygen anions generated by the region's anti-sputtering effect. Studies have shown that anti-sputtering effect is not exactly the same high-energy oxygen ion bombardment effect, but also thin films deposited by sputtering zone oxidation extent. Anti-sputtering effect reduces the target utilization and impact of film in the aluminum content should be avoided as much as possible.
　　7, by comparing the experimental study of ZnO and AZO thin films in air and hydrogen in the annealing and defect analysis of the behavior of interstitial oxygen on the film properties, and further clarify the effect of injection of oxygen ions bombarded the film physical properties of the mechanism. Also by comparing the experimental analysis and discussion of RAS zinc, aluminum sputtering target AZO film properties were limited reasons.
　　8, 500 ℃ annealed by hydrogen to obtain resistivity 4.5 × 104Ω.cm, carrier concentration of 5.15 × 1020cm-3, the migration rate of 24.6 cm2V-1s-1, 550 nm wavelength transmission rate of 89% of the AZO films . Annealed AZO films stable, have practical value.
　　Degree Year: 2010