【作者】 李凤丽；

【导师】 杜祖亮；

【作者基本信息】 河南大学 ， 凝聚态物理， 2009， 硕士

【摘要】 具有金红石型结构的SnO₂是一种宽带隙n型半导体材料,其室温禁带宽度为3.6eV（300K）。由于其独特的光电性质及稳定的化学性质,已被广泛的应用在光电器件以及还原性气体检漏的气敏元件等领域。一维的SnO₂纳米结构由于具有大的比表面积和量子尺寸效应,在气敏传感器、太阳能电池、透明导电电极、催化剂载体等方面有着潜在的应用。本文通过热蒸发SnO₂粉末方法制备SnO₂纳米带,然后采用浸泡的方法合成Ag/SnO₂纳米带的复合结构。同时结合电场组装的方法和表面光电压技术分别对SnO₂纳米带复合前后的光电特性进行了研究。在第二章我们采用热蒸发的方法制备出了SnO₂纳米带,通过SEM、TEM、SAED和XRD对样品进行表征,并对样品的荧光特性进行了分析。第三章我们将纳米带超声分散在无水乙醇溶液中,运用电场组装的方法将单根SnO₂纳米带搭接在Au电极上,然后我们对组装成功的SnO₂纳米带的光电性质进行了测量和分析,发现SnO₂纳米带的I-V特性曲线在暗态下表现为非对称的非线性特性,加光后电流有明显的增大。对非对称非线性I-V特性进行分析,认为非线性的I-V曲线是SnO₂纳米带与Au电极之间形成了两个背靠背的肖特基势垒,通过具体的计算和光照实验证明了在电场组装过程中表面态所引起的势垒高度差的不同导致电学性质的非对称。第四章把制备好的SnO₂纳米带浸泡在Ag胶体溶液里,采用简单的浸泡法合成Ag/SnO₂纳米带的复合结构,然后利用电场组装的方法将单根的Ag/SnO₂纳米带搭接在Pt电极上,对其电输运性质进行了研究,发现SnO₂纳米带复合上Ag粒子后,跟纯的SnO₂纳米带相比电流很小,原因可能是由于局域的肖特基结在Ag粒子附近的SnO₂纳米带表面形成耗尽层,减小了纳米线的有效传导通道,电流减小。然后通过表面光电压技术（SPV）研究Ag粒子是如何来影响SnO₂纳米带的表面光电性质,对纯的和复合Ag纳米粒子的SnO₂纳米带进行SPV测试,结果表明由于Ag纳米粒子的存在使得复合后的SPV响应减小,对减小的原因进行了分析。更多还原

【Abstract】 As an important wide band n-type semiconductor, SnO₂ possesses many unique optical and electrical properties which have been widely used in optoelectronic devices and the reduction of gas leak detection gas sensors. One dimensional （1D） SnO₂ nanowires or nanobelts have been reported to have some different characteristics from the bulk crystal due to its large surface-to-volume ratio which make them very important for its potential applications in gas sensors, dye-based solar cells, transparent conducting electrodes, and catalyst supports. In this paper, SnO₂ nanobelts were synthesized by thermal evaporation of SnO₂ powder. As-prepared SnO₂ nanobelts were immerged into the Ag colloid and obtained the Ag/SnO₂ nanobelts. Single SnO₂ nanobelt or Ag/SnO₂ nanobelt is aligned onto the paired Pt electrodes using AC electric field assembly, and its optoelectric and transport properties were studied. In addition, we also studied the Surface photovoltage （SPV） of SnO₂ nanobelts and Ag/SnO₂ nanobelts, respectively.In Chapter 2, SnO₂ nanobelts were synthesized by thermal evaporation of SnO₂ powder. The morphology and structure of the products were characterized by SEM、TEM、SAED and XRD. The room temperature photoluminescence spectra were studied.In Chapter 3, the as-synthesized SnO₂ nanobelts were placed in ethanol and ultrasonicated to disperse the bundles into individual nanobelts. A single SnO₂ nanobelt was assembled on a pair of Au electrodes by dielectrophoresis, and the I-V curves were showed nonlinear and asymmetry under dark condition and the current increased under UV illumination. The nonlinear electrical transport behavior indicates that the back-to-back Schottky barriers structure is formed. Through measurement of the I-V curve and the calculation of barrier height difference under illumination, it is found that the electrical asymmetry results from the asymmetric barrier height of the two Schottky barriers, which are dominated by the surface states of NB caused by O₂ adsorption in the electric assembling process.In Chapter 4, as-prepared SnO₂ nanobelts were immerged into the Ag colloid and obtained the Ag/SnO₂ nanobelts. The as-synthesized samples were characterized by SEM, EDS, TEM and XPS. Single Ag/SnO₂ nanobelt is aligned onto the paired Pt electrodes using AC electric field assembly and its transport properties were studied. The results demonstrated that the formation of Schottky junction lead to the current decreased. The Surface photovoltage （SPV） of SnO₂ nanobelts and Ag/SnO₂ nanobelts were also studied.更多还原