【作者】 何维凤；

【导师】 赵玉涛；

【作者基本信息】 江苏大学 ， 材料加工工程， 2005， 硕士

【摘要】 ZnO透明导电薄膜作为一种重要的新兴光电子信息材料,不仅具有在可见光区高的透过率、在红外区高的反射率以及较高的电导率等光电特征,而且具有成本低、资源丰富（约是In含量的1000倍）、无毒性、高的热稳定性和化学稳定性等优势,有望成为ITO薄膜的替代产品,并在太阳能电池、液晶显示器、电磁防护屏等领域具有广阔的应用前景。本课题研究以纯度为99.9%的ZnO纳米粉体和99.99%的Ga₂O₃粉体为原料,采用了冷等静压法+高温烧结,优化工艺获得质量优良的ZnO系靶材,研究射频溅射法在硬质衬底（普通玻璃）和柔性衬底（聚酰亚胺,简称PI）上制备ZnO透明导电薄膜,利用XRD、EDS和AFM等现代分析手段研究了薄膜的化学成份、相组成和微观形貌,研究了薄膜的光学和电学特性,并对薄膜的透光和导电机制进行了讨论。 实验结果表明:以纯度为99.9%的ZnO纳米粉体和99.99%的Ga₂O₃粉体为原材料,采用冷压成型和优化的烧结工艺,成功制成了具有27.72%的收缩率的单一ZnO靶材和27.65%的收缩率的ZnO/Ga₂O₃复合靶材,并满足了实验用射频磁控溅射制备ZnO系薄膜靶材的高致密度要求。 射频磁控溅射法制备ZnO系薄膜的研究表明:采用纯度为99.9%的自制ZnO系靶材为溅射靶,设计和优化了射频磁控溅射制备ZnO系薄膜的工艺,并分别以普通玻璃和有机聚酰亚胺（PI）为衬底在高纯的氩气中成功制备了单一ZnO薄膜和ZnO/Ga₂O₃复合薄膜,研究了主要溅射参数对薄膜的微观形貌（AFM图）的影响规律。获得的最佳的工艺条件为:溅射功率70W、溅射氩气分压0.1Pa,靶材—基体间距70mm,溅射时间60min,真空度为6×10^-5Pa。 利用X射线衍射仪（XRD）、电子探针（EPMA）、能谱分析（EDS）、原子力显微镜（AFM）等分析手段对所制得的薄膜成分、相组成及微观形貌研究表明:实验制备的ZnO系透明导电薄膜为多晶六角纤锌矿结构,具有（002）面的择优生长取向,其中Ga原子以替位式出现在晶格中。溅射过程中无需对衬底进行加热,溅射后也无需对薄膜进行退火处理;ZnO系透明导电薄膜呈柱状生长,结构非常紧密,并且离开玻璃衬底越近,晶粒越小。ZnO系表面微观形貌为细小岛状的连续膜。 划痕法测试薄膜—基体界面结合强度（附着力）结果表明:在玻璃衬底和聚酰亚胺衬底上制备的高质量的薄膜都具有良好的附着性。其中,聚酰亚胺衬底上制备的薄膜经过多次折叠,没有发现龟裂和脱落现象。 ZnO/Ga₂O₃薄膜的光学特性测试和分析表明:在玻璃衬底和聚酰亚胺衬底上沉更多还原

【Abstract】 ZnO transparent conducting oxide （TCO） film is one of important opto-electronic information materials, which has not only high optical transparence in the visible region, high optical reflectance in the infrared region and high electrical conductivity but also much advantages, such as low cost, abound resources（about 1000 multiple of In content ）, non-toxicity, high heat stability and chemical stability etc. It has extensive prospects in the fields of solar cell batteries and liquid crystal display devices, and it is hopeful to become the succedaneum of ITO film. In the present work, ZnO nano-sized powders with the purity of 99.9% and Ga₂O₃ powders with the purity of 99.99% are adopted as raw materials. The ZnO/ Ga₂O₃ sputtering target is successfully prepared by pressing at room temperature under isostatic pressure and by sintering at high temperature according to optimum sintering technique. The ZnO/ Ga₂O₃ film is successfully deposited on hard substrate （ordinary glass） and flexible substrate （polymide, PI） by radio frequency magnetron sputtering （RF-MS）. With the help of modern analyzers, for examples, XRD、 EDS and AFM, the chemical composition, phase constitution and morphology of ZnO/ Ga₂O₃ film are analyzed. The optical, electrical and meehanical properties are studied. The transmission and conduction mechanisms of ZnO/ Ga₂O₃ film are also discussed.The experiment results show that ZnO nano-sized powders with the purity of 99.9% and Ga₂O₃ powders with the purity of 99.99% are adopted as raw materials. Pure ZnO target with shrinkage ratio of 27.72% and ZnO/Ga₂O₃ composite target with shrinkage ratio of 27.65% are successfully prepared by pressing at room temperature under isostatic pressure and by sintering at high temperature according to optimum sintering technique. So these targets possess the high density so as to meet the need for RF sputtering target in the present experiment.The research on ZnO films prepared by RF magnetron sputter indicate that ZnO and ZnO/ Ga₂O₃ films are successfully deposited on ordinary glass substrate and PI substrate in pure Argon gas when self-made ZnO targets with the purity of 99.9% are used as sputtering target. The influence of sputtering technical parameters on the morphology of ZnO films is studied by AFM. The optimal sputtering parameters are as follows, sputtering power 70W, sputtering argon gas pressure 0.1Pa, the distance between the target and the substrate 70mm, sputtering time 60min, sputtering vacuum 6×10^-5Pa.With the help of modern analyzers, XRD、 EPMA、 EDS and AFM, the chemical composition、 phase constitution and morphology of ZnO film are analyzed. Resultsshow that as-deposited ZnO films are hexagonal wurtzite polycrystalline structure. The preferential orientation of （002） is for all deposited films, and Ga ions appear in crystal lattice in form of displacement. No heating on the substrate during the sputtering and no annealing treatment are necessary for as-deposited ZnO films. ZnO films grow in the orientation of c-axis, and have dense structure. The crystal grains of ZnO films become smaller when the distance is closer the substrate.The results of interface bonding strength tested by scarification method show that ZnO films sputtered on glass substrate and PI substrate both have good adhesion properties. Furthermore, there are no formation of cracking and pull-out phenomenon appeared after folding the films deposited on PI substrate for several times.The optical property test and analysis of ZnO/Ga2O3 films show that the ultimate transmittance of ZnO/ Ga2O3 films deposited on glass substrate and PI substrate is 94% and 80% respectively. Moreover, because flexible substrate material has narrow band gap 2.82eV, transmittance curve of ZnO/Ga2O3 films deposited on PI substrate different from that on glass ones. It moves to the direction of long wave. The transparent mechanism of ZnO films lies in that ZnO is direct high-gap semiconductor material. Energy band of valence electron is full, so it can’t absorb photon to move freely, while photon energy is too low to make valence electron transit to conduction band. Furthermore, the flaws in ZnO and doping can change its forbidden band width. Therefore, in order to improve the transmittance of ZnO films, its growth conditions should be controlled to get appropriate crystal grain size, good orientation and dense structure.The electrical property test and analysis of ZnO/Ga2O3 films indicate that the minimum electrical resistivity of ZnO/ Ga2O3 films deposited on glass substrate and PI substrate is 2.25><10’3Q.cm and 7.51><10"2D.cm respectively. The resistivity of ZnO/Ga2O3 films deposited on glass substrate is higher than that on PI substrate. It may because of non-activity and worse lattice matching with ZnO films on the surface PI substrate. The resistivity of pure ZnO films is high enough to reach 106Q.cm, but ZnO/Ga2O3（ or ZnO: Ga） is much less to 10’3Q.cm. The electricity-conducting mechanism of ZnO films is that ZnO has wurtzite structure, and there are bigger interstices in its tetrahedron and octahedron structure. And the radius of Zn atom is shorter than O atom, so it is easy to enter interstice to form Znj flaw. During doping,Ga3+ take the place of Zn2+ and provide a redundant electron as current carrier, which make current carrier concentration increase with doping proportion.更多还原