一维纳米肖特基势垒的双向电学输运特性研究

发布时间：2018-03-01 16:42

本文关键词： ZnO纳米带、肖特基势垒电流输运特性双向输运特性　出处：《河南大学》2015年硕士论文　论文类型：学位论文

【摘要】：一维结构的氧化物半导体材料由于其潜在众多的应用,如:紫外激光器,光敏二极管,气敏传感器和紫外光探测器等,以及其作为构筑光电器件的结构单元受到越来越多的研究者的关注。ZnO是一种典型的n型宽禁带半导体,由于其具有宽禁带(3.37 eV)和大的激子结合能(60 meV),成本低廉,强的耐辐射性和易于制造等优点成为一维半导体材料领域最优异的材料之一。在构筑器件时,一维ZnO纳米材料不可避免地要与金属电极接触。n型的ZnO与高功函数的金属(如Au、Pt等)接触时,易于形成肖特基接触。研究发现,肖特基接触势垒对诸多器件(如紫外光探测器、气敏传感器等)的性能有很大的影响。关于外加偏压对肖特基势垒的影响以及肖特基势垒的双向电学输运特性的研究鲜有报道。由于肖特基势垒具有很好的高频特性,并且肖特基二极管相对于pn结有较低的开启电压,因此基于肖特基势垒双向输运特性发展新型的放大、逻辑器件具有重要的应用前景和意义。基于课题组在该方面的研究,在本论文中,我们研究了在两电极和三电极情况下的I-V曲线。发现,在三电极测试时,中间电极与纳米线形成的肖特基势垒高度有所增加。我们对势垒高度增加的原因进行了分析。最后,我们利用导电原子力显微镜的探针替代中间电极,重新进行了测试。发现在这种条件下,肖特基势垒要做双向的电输运。我们研究了肖特基势垒的双向输运特性,并基于该特性提出了一种新型的电子器件。具体的研究工作包括以下几个部分:首先在第二章中:我们采用ZnO粉末和活性炭粉末做原料,利用化学气相沉积chemical vapor deposition(CVD)方法制备出了ZnO纳米带,并对上述合成的ZnO纳米带进行了X射线衍射谱、紫外可见吸收光谱、场发射扫描电子显微镜、透射电子显微镜等一系列表征,证明我们所制备的纳米带具有良好的结晶性并且缺陷较少。利用交流电介电泳组装(电场组装)的方法实现了单根ZnO纳米带三电极器件的构筑。通过I-V曲线,我们得知ZnO纳米带与三个电极都形成了良好的肖特基接触。在成功构筑器件的基础上,在第三章中,我们通过两电极和三电极I-V曲线的比较,发现在三电极测试的模式下,ZnO纳米带与金电极接触形成的的肖特基势垒高度有所增加,并研究了势垒高度增加的原因。我们认为在三电极测试时,由于肖特基势垒需要进行双向电流输运,随着反向偏压的增加,肖特基势垒的有效接触长度变大,耗尽区的内建电场增强,导致肖特基势垒高度增加。在第四章中,我们利用导电原子力显微镜的探针取代器件的中间电极,重新进行了测试。通过对数据的分析,我们发现,原子力显微镜探针构成的中间电极处尽能形成一个势垒。同时,由于原子力探针与纳米带的接触面积较小、施加的力较小,所测得的电流较小,且只有电极2的电流,不能进行势垒高度的计算。但是,电流的变化率达到了168%,高于微电极的60%。这主要归因于势垒耗尽区的变化比微电极更大。
[Abstract]:One dimensional structure of oxide semiconductor materials because of its potential applications, such as: many of the UV laser, photosensitive diode, gas sensor and UV detector, and its structure as a structural unit of optoelectronic devices has attracted more and more researchers' attention to.ZnO is a typical n type wide bandgap semiconductor, because of its wide band gap (3.37 eV) and large exciton binding energy (60 meV), low cost, strong radiation resistance and easy manufacturing has become one of the most excellent materials in the field of one-dimensional semiconductor material. In the construction of the device, one dimensional ZnO nano materials will inevitably have to contact.N and metal electrode ZnO with high work function the metal (such as Au, Pt etc.) contact, easy to form a Schottky contact. The study found that the Schottky barrier height on many devices (such as UV detectors, gas sensors and so on) the performance has a great influence. With the bidirectional electrical effect of bias on the Schottky barrier and Schottky barrier transmission there are few reports on transport properties. Due to the Schottky barrier has excellent high frequency performance, and compared with the Schottky diode low turn-on voltage of PN junction, so to double Schottky barrier transport development model based on the amplification, has important application prospect and significance the logical device. The research of this aspect in the research group based in this paper, we study the I-V curve in the two and three electrodes. The case found in the three electrode test, Schottky barrier intermediate electrode and nanowire formation is highly increased. The reason why we highly increase on the barrier is analyzed finally, we use conductive AFM probe instead of the intermediate electrode, re tested. In this condition, the Schottky barrier to do two-way Electrical transport. We study the two-way Schottky barrier properties, and based on the characteristics of a new type of electronic device. The research work includes the following parts: first, in the second chapter: we use ZnO powder and activated carbon powder as the raw material, chemical vapor deposition by chemical deposition gas (CVD) method to fabricate ZnO nanobelts, and the synthesis of ZnO nanobelts were characterized by X ray diffraction spectroscopy, UV Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and a series of characterization, we proved that the prepared nano belt has good crystallinity and less defects. Using the assembly AC dielectrophoresis (electric field assembly) to build a method to realize the single nano ZnO three electrode devices. Through the I-V curve, we learned that ZnO nanobelts and three electrodes are formed good Schottky barrier contact. Based on the successful construction of the device, in the third chapter, we compare two electrodes and three electrodes of I-V curve, found in the three electrode test mode, ZnO nano belt and gold electrode contact forming a Schottky barrier height increase, and study the reason of barrier height increases. We believe that in the three electrode during the test, because the Schottky barrier need to transport a bidirectional current, with the increase of reverse bias, the effective contact length of Schottky barrier becomes large, the depletion region of the built-in electric field enhancement, leading to the Schottky barrier height increases. In the fourth chapter, we use conductive AFM probe to replace the intermediate electrode device, re test. Through the analysis of the data we found that the intermediate electrode atomic force microscope probe which can form as a barrier. At the same time, because the atomic force probe and nano contact zone The area is smaller, the applied force is smaller, the current measured is smaller, and only the current of electrode 2 can not carry out the calculation of barrier height. However, the change rate of current reaches 168%, which is higher than that of microelectrode 60%., which is mainly attributed to the change of barrier depletion area larger than that of microelectrode.

【学位授予单位】：河南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN311.7

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