| 题名 | 宽禁带半导体材料ZnO的生长及其性能研究 |
| 作者 | 杨锡林 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 杭寅 |
| 关键词 | CVT法 水热法 显微镜 闪烁晶体 X射线 ZnO薄膜 SrTiO3 |
| 其他题名 | Study on Growth and Properties of Wide Band-gap Semiconductor Material Zinc Oxide |
| 中文摘要 | 直接宽禁带半导体材料ZnO是一种多功能光电材料，常温下呈稳定的纤锌矿结构，禁带宽度为3.36eV,特别是其激子结合能高达60meV。ZnO自身的优点使其成为制备光电子器件（LD，LED）的优良材料，极具开发和应用的价值。自1997年，ZnO室温下的紫外受激发射实现后，吸引了众多科研工作者的兴趣，成为当前的研究热点。 目前有关ZnO的研究主要集中在晶体生长和薄膜外延:(1) ZnO晶体的生长方法主要有水热法、气相法、助熔剂法和压力熔体法等。其中水热法是在低饱和度的条件下生长ZnO晶体，生长温度较低，容易生长大尺寸的ZnO晶体并且热应力小，是目前ZnO晶体生长的主要方法。（2）气相法是使蒸汽压较大的材料在高温区升华而传输至低温区进行结晶生长的方法。气相沉积法生长的晶体纯度比相同原料的水热ZnO晶体纯度高，且操作简单、生长装置成本低、生长周期较短，其缺点是生长难以控制。这两种方法是目前最主要的晶体生长方法，所以本论文开展了ZnO晶体的水热法和CVT法生长并对所得晶体的性能进行了比较分析研究。另一方面，ZnO薄膜的外延方法有很多种，常用的有磁控溅射、化学气相沉积(CVD)、脉冲激光沉积(PLD)、金属有机化学气相沉积(MOCVD)、分子束外延(MBE)、电子束蒸发等。脉冲激光沉积(Pulsed Laser Deposition)是近年才发展起来的一种真空物理沉积工艺，而MOCVD是一种成熟的薄膜生长技术，已经在工业生产上得到广泛应用。 本论文研究内容主要包括以下几方面: 1） 利用水热法生长出尺寸为33mm×27mm×8mm的ZnO晶体,+C面区域抛光后基本为无色透明。采用化学气相传输法(CVT),以GaN/Al2O3为籽晶生长出18mm×15mm×1mm的ZnO晶体。结合实验结果和理论，研究了对CVT过程的主要影响因素。比如：输运剂的量对晶体和原料的影响。以及生长气压，温度梯度等的影响。发现高输运剂浓度和高温度梯度、低输运剂浓度和小温度梯度都不利于CVT法生长ZnO晶体。本实验中的最佳温度梯度为45℃左右，输运剂与原料的质量浓度比为C∶ZnO＝1∶45。 2） 在结构、光学性能和杂质含量上对两种方法生长的ZnO晶体进行了表征和分析比较。XRD谱图表明CVT法所得最优质量的ZnO晶体（0001）面FWHM为35弧秒，优于本实验中的水热ZnO晶体，但CVT-ZnO晶体生长的重复性和稳定性有待提高。紫外可见波段的吸收曲线显示了两种方法生长的ZnO晶体的紫外吸收边都位于395nm，相对带边吸收376nm有一定的红移，说明晶体中均存在一定的浅杂质能级。Xe灯激发的荧光谱表明退火之后CVT-ZnO晶体的带边发光性能相对水热-ZnO晶体有了明显的提高。本论文还探讨了ZnO晶体作为超快闪烁材料的潜在应用前景，其中CVT法生长的ZnO晶体在X-ray激发下出现了明显的带边激子发光峰。 3） 采用脉冲激光沉积法（PLD）和金属有机化学淀积(MOCVD)在(111)SrTiO3 、(111)MgAl2O4、(001)LaAlO3等衬底上外延生长ZnO薄膜。对PLD法与MOCVD法所制备的ZnO薄膜进行了结构、光学性能等方面的表征；重点探讨了温度、衬底和生长方法对ZnO薄膜质量的影响。根据实验结果我们可以断定（111）SrTiO3可以作为ZnO薄膜外延生长的优质衬底材料。 关键字: CVT法，水热法，显微镜，闪烁晶体，X射线，ZnO薄膜 ，SrTiO3 |
| 英文摘要 | ZnO a wide band-gap semiconductor (3.37 eV at room temperature) with the high exciton binding energy of 60 meV. It has the same Wurtzite structure as GaN and the mismatch between them is smaller than 2% of the (0001) plane，Because of its excellent properties with low dielectric constant and high chemical stability semiconductor，It is a promising material in Many fields, especially in the optoelectronic fields. Zn0-based semiconductor optoelectronic devices include ultraviolet detector, light emitting diodes (LEDs) and laser diodes (LDs), etc. Since ultraviolet (UV) lasing from Zn0 was realized in 1997, the study on Zn0 has attracted the increasing intrests of scientists all over the world. Currently the methods for growing ZnO include flux, hydrothermal, chemical vapor transport, and high pressurized melt growth method. Hydrothermal method is the most successful method with the lowest growth temperature and the super-saturation is relatively low too. These advantages made it a good method for growing large single crystals and with less costs than other methods. So, we grown ZnO single crystals by hydrothermal method and study the properties of ZnO. CVT also is a important method for growing ZnO crystal and it is easy to got high-quality bulk ZnO wafers by it with low costs. In this method, the ZnO materials is transported to the cooler place from hot place and grown on the substrates. Now, ZnO epitaxial films have been grown by various techniques such as Pulsed Laser Deposition (PLD), Metal-organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), E-beam Evaporation, Sputtering and Atomic Layer Epitaxy (ALE).PLD is a methods, devloped in recent years, has many advatage in growth of films.while MOCVD has applied in commecial activties. In this paper, our reseach contents include: (1) By improving former technics, Growing ZnO single crystals under hydrothermal condition with the high-purity materials. +c districts of ZnO single crystal is colorless and transparent after polised, the largest crystal’size is 33mm×27mm×8mm.additionally. we got ZnO single crystal (18mm×15mm×1mm）on GaN/Al2O3 by chemical vapor transport methods by CVT and discussed several factors in process of CVT，such as：pressure，temperature gradient and concentration of materials. According to our research，we foud it is so hard to grow the ZnO crystal under low temperature gradient and smaller Transport Agent consentration like as the opposite condition. (2) Compared the properties ZnO crystal grown by hydrothermal and by CVT, the XRD drawing shows the (0001)FWHM of the high quality ZnO single crystal growed by CVT is only 35aresec,but stability and repeatiality of the process need to be improved furtherly. In UV/VIS absorption spectra，Absorption edge shifted toward to long wave because of impurity level.Additionally，we also measured the X-ray emission spectrum of ZnO crystal. (3) Zn0 thin films were deposited on (111)SrTiO3, (111)MgA1204 和(100)LaAlO3 substrates by PLD and by MOCVD. The paper engaged in the research work of influences of different growth conditions on characteristics of Zn0 films, Such as different growth temperatures, Substrates and epitaxial methods. According our conclusion，it is obvious to grow the high quality ZnO thin films on (111)SrTiO3 Key words: CVT. Hydrothermal. X-rays. Microscope. Scintillator. ZnO thin films. SrTiO3 |
| 语种 | 中文 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16474]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 杨锡林. 宽禁带半导体材料ZnO的生长及其性能研究[D]. 中国科学院上海光学精密机械研究所. 2007. |
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