【作者】 李兵；

【导师】 程纲；

【作者基本信息】 河南大学 ， 材料学， 2012， 硕士

【摘要】 具有纤锌矿结构的ZnO是一种直接宽带隙的n型半导体材料,在室温下的禁带宽度为3.4eV，激子结合能高达60meV，这些独特的性质引起了人们广泛的研究。而作为一维的ZnO纳米结构由于具有大的比表面积、高的表面活性以及量子尺寸效应，能制备出性能优异的紫外光电探测器、整流器件等。在本论文中，我们通过I-V-T研究了肖特基接触的电学输运性质，利用高真空、紫外光（UV）实现了对肖特基势垒高度的控制。研究发现在真空和UV条件下，氧气从表面脱附的过程中，会产生一个吸附-脱附的动态过程。另外，我们还通过I-V-T研究了肖特基接触的整流性质，观察到正弦波在正向偏压下具有截止特性。第二章中我们采用vapour-liquid-solid (VLS)和水热合成的方法分别制备出ZnO纳米线，并对两种方法制备的ZnO纳米线进行各项表征。利用在位电场组装的方法成功实现了单根ZnO纳米线的组装。第三章中我们首先研究了Au与单根ZnO纳米线的形成的肖特基接触在30-490K下的I-V性质，研究发现当测试环境由室温大气转变成高真空并长时间放置后，肖特基接触有向欧姆接触转变的趋势，这种转变主要由势垒高度的降低和隧道电流的增大所引起。在真空、UV下会引起电流增大，达到稳定，关掉UV，长时间在真空下放置后，加UV能再次引起电流的显著增大。这表明吸附氧的脱附不是一次性完成的，它的脱附与所处的位置有关。第四章我们发现Au/ZnO纳米线/Au的接触在暗态下具有良好的整流性质。在I-V-T的测试过程中，我们发现这种整流性质与温度和电压有关。真空下，随着温度的升高，整流性质变的更好，达到饱和电流所需的偏压更小。使用10-1000Hz、10Vpp的正弦波、方波作为输入波形，输出波形在正向偏压变下表现出截止特性，但是在高频（1000Hz）下的波形特征会发生了扭曲。在UV照射下，波形的振幅相比于暗态时增加超过了10倍。更多还原

【Abstract】 ZnO as a direct wide band gap3.37eV (300K) semiconductor with hexagonal wurtzite structure andlarger exciton binding energy60meV has caused a widespread research. One dimensional (1D) ZnOnanowires or nanobelts can be prepared as more excellent ultraviolet detectors, gas sensors, lasertransmitter due to its large surface-to-volume ratio, high surface activity and the quantum size effect. In thispaper, we studied the electrical transport properties of Schottky contacts through I-V-T characteristics, andobserved a persistent photoconductivity effect by means of controlling the Schottky barrier height throughhigh vacuum and UV. In additional, we also studied the rectifying behavior of the schottky contacts inI-V-T characteristics and found the barrier height inhomogeneities in low temperature. Under smallfrequency sine wave and forward bias, a cut-off characteristic was observed.In Chapter2, ZnO nanowires were synthesized by vapour-liquid-solid and hydrothermal method. Themorphology and structure of the products were characterized by SEM、TEM、HRTEM and XRD, then asingle ZnO NW was aligned by AC electric field assemblyIn Chapter3, We first studied the single ZnO nanowire Schottky contacts with the I-V characteristicsin the30-490K. We found schottky contacts trends to ohmic contacts when the test environment waschanged from the atmosphere at room temperature into the vacuum and placed a long time. This shift wasmainly caused by the lower barrier height and tunneling current increases. Under vacuum and UV light, weobserved the photocurrent was first enhancement and then stable, turned off the UV light and placed invacuum for a long time, the photocurrent had a significant increase once again under UV light,which is apersistent photoconductivity effect. This showed that the chemisorbed oxygen was not desorptioncompletely from interface at one time, and chemisorbed oxygen’s desorption was relate to its location. Sowe need chemisorbed oxygen to get in the easy desorption in order to get a high switching ratio under UV.In Chapter4, the new simple of Au/ZnO nanowire/Au exhibited clear rectifying behavior under dark.We also found the rectifying behavior had relation to temperature and voltage in I-V-T testing process. With increasing temperature, rectifying behavior would not only become better but also need much smallbias to reach a saturation current. Loading10-1000Hz and10Vpp sine, square wave in the sample, wewould find sine wave in the forward bias became into cut-off characteristics in a small frequency. Butsquare wave deviated from the original rectangular wave characteristics in high frequency (1000Hz).Under UV, the amplitude of the wave enlarged more than10times compared to the dark state.更多还原