【作者】 张秋香；

【导师】 朱自强；

【作者基本信息】 华东师范大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 ZnO是一种重要的直接宽带隙半导体，室温下禁带宽度为3.37eV，激子束缚能为60meV，因此在制造电子和发光器件上有巨大潜力。而纳米ZnO则表现出与体材料明显不同的电学、磁学、光学、化学等性质，是目前纳米材料的研究热点之一．本论文介绍了不同形貌和不同尺度的ZnO结构的制备和表征，同时对它们的光学和场发射等方面的性质进行了研究。本论文的主要内容和创新点如下：1．利用热蒸发和硫脲溶液浸泡两步法制备了性能优良的ZnO纳米线，并且研究了这些ZnO纳米线的光致发光和场发射特性。与直接采用热蒸发方法生长的ZnO纳米线相比，由该方法得到的ZnO纳米线表现出更好的紫外发光特性；场发射特性表明经过溶液浸泡后的ZnO纳米线的开启电场和阈值电场值都有所降低。通过浸泡其他形貌的ZnO纳米结构，我们发现浸泡以后纳米ZnO结构的形貌会有所改变。我们还发现如果浸泡过程中溶液浓度过高或者是浸泡时间过长，纳米结构的数量会减少，甚至会消失。2．通过改变热蒸发过程中的源材料和衬底的位置等生长条件，首次制备了纳米樱桃，纳米蜈蚣，纳米纺锤和长纳米棒四种不同形貌的ZnO纳米结构。利用XRD和SEM分析了这些氧化锌纳米结构的微结构和形貌特征，发现氧化锌的形貌与生长条件有很大关系。对这些氧化锌纳米结构进行了光致发光谱和场发射性质的测试并分析了不同形貌的ZnO纳米结构对这两种性质的影响。最后我们通过改变生长温度又生长出了其他形貌的ZnO纳米结构。并且简单分析了一下不同形貌的ZnO纳米结构的生长机理。3．通过利用与以往制备纳米梳和纳米带不同的源材料，我们在国际上首次制备了超长的ZnO纳米结构—厘米级别的纳米梳和纳米带。这些宏观尺度的纳米梳和纳米带的产量比较多，生长的重复性也比较好。制备的这些宏观结构长度从毫米级别到厘米级别，其中最长的接近2cm。因此通过用一次性针管进行剥离可以很容易的分离出了单个的纳米梳和纳米带并进行相关的测试。SEM测试表明这些超长纳米梳的梳齿直径在100～350nm之间；而超长纳米带的宽度在20μm左右，厚度约是50nm。随后我们对这些结构进行了光致发光谱的测试，发现这些宏观尺度的纳米梳和纳米带的光学性质与以前报道过的微观尺度的纳米梳和纳米带结构没有明显的区别。通过对超长纳米梳结构进行TEM测试，我们发现这些纳米梳状结构的厚度和梳齿之间的距离都是很均匀的；选择区域的电子衍射像表明这些梳状结构是单晶的；通过对超长纳米梳进行光学表征，我们观察到了清楚的干涉条纹。最后简单分析了这些超长ZnO纳米梳和纳米带的生长机制。更多还原

【Abstract】 ZnO is an important wide band semiconductor with a band gap of 3.37 eV and exciton binding energy of 60 meV, which makes it a promising material for electronic and optical devices. Nano-ZnO has some different properties which are different from the bulk materials in electricity, magnetics, optics and chemistry, so the research on it becomes one of the most important works. In this article, we introduce the synthesis and characterization of different ZnO nanostructures, at the same time, the photoluminescence and field emission properties of them are also been studied. Main concludes and results are as follows:1. ZnO nanowires with excellent photoluminescence and field emission properties were synthesized by a two-step method. Compared with those that were fabricated by a thermal evaporation method, the ZnO nanowires here shows better UV luminous property and there is a 5nm blue-shift. The turn on field and the threshold field of the immersed ZnO nanowires are much lower. Other morphologies of ZnO nanostructures are also changed by immersing them into TU solution. We also found that if we immerse these nanostructures into too high concentration solution or for too long time, the quantities of the ZnO nanostructures will decrease or even all of the nanostructures disappear.2. By changing the experimental conditions, we firstly fabricated nanocherries, nanocentipedes, nanospindles and long nanorods ZnO structures with the thermal evaporation method. XRD and SEM are used to study the morphologies and structures of these ZnO nanostructures. We found the nanostructures are closely relative to the growth conditions. And we found that the ZnO nanostructures can affect the photoluminescence and field emission properties. At last, we obtained other ZnO structures by changing the growth temperature and analyzed the growth mechanisms of these ZnO nanostructures.3. We successfully synthesized centimeter-long nanocombs and nanobelts structures for the first time by using sources that are distinct from the reported before. The yield of these microscopical structures is great and the growth of them can be repeated. The length of these nanostructures is from millimeter to centimeter andthe longest one of them is about 2cm, so we use a one-off needle tubing easily separate one nanocomb or a nanobelt from the samples and test some characteristics of them. The SEM images of them show that the branches of the nanocombes structures are about 100nm-350nm; the width of the nanobelts is 20μm and the thickness of them is about 50nm. Then the PL characteristics of the ultra-long nanocombs and nanobelts were studied and we found that there were no differences of the PL characteristics between the ultra-long nanostructures and the nano/meter-long structures. We also investigated the TEM and optical interference of the centimeter-long nanocombs and found that the thickness of them is well-proportioned and the distance between the branches is also even. SAED indicates that these ultra-long nancombs are single crystal. In the end, we discussed the growth mechanism of the ultra-long nanocombs and nanobelts.更多还原