【作者】 李辉；

【导师】 李含冬；

【作者基本信息】 电子科技大学 ， 电子信息材料与元器件， 2015， 硕士

【摘要】 基于Bi2Se3、Bi2Te3和Sb2Te3的薄膜及其混晶合金结构不仅是最优异的热电基础材料,最近还被揭示出是强拓扑绝缘体,因此有可能成为狄拉克固态量子体系应用的基础材料。本文采用物理气相沉积薄膜的方法,借助真空管式炉制备Bi2Se3的单晶薄膜,在此基础上进行了该系列化合物的三元及四元合金薄膜生长研究,通过一系列测量手段对其结构和性能进行了分析和表征,并重点探讨了硒化铋四元合金薄膜的电学输运性质和三元合金薄膜的光电特性。具体工作内容和概括如下:1.物理气相沉积是一种简单实用的薄膜生长技术。我们自行搭建这样一套系统,并通过物理气相沉积法,制备出了质量较好的Bi2Se3单晶薄膜,通过XRD的面内和面外测试证明薄膜c轴择优取向生长,SEM图像表明其表面存在三角螺旋对,并且间接证明拓扑绝缘体的层状结构,为后期多元合金薄膜的制备提供了参照和技术支持。2.依照方案制备Bi2Se3和Sb2Te3的四元合金薄膜(BixSb2-x)(SeyTe3-y),经过改变生长条件,成功得到了四元合金薄膜。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱定量分析(EDS)、霍尔效应和拉曼光谱仪对合金薄膜晶体结构、表面形貌、成份、电学输运特性和散射机制等性能进行了研究,发现随着x和y的不断增大,其衍射峰位由Sb2Te3的衍射峰位向Bi2Se3衍射峰位移动,同时,表面平整度越来越差,缺陷越来越多,载流子浓度逐渐减小,迁移率逐渐增加,拉曼散射峰位整体红移。四元合金薄膜在热电领域有很大的潜在研究价值。3.通过向Bi2Se3掺杂钙得到三元合金薄膜Bi2-xCaxSe3,对其晶体结构和表面形貌进行研究,发现其主晶相没有发生变化。通过综合物性测量系统研究它的电学输运特性,发现载流子导电类型翻转为P型,并且载流子浓度较单晶薄膜有明显下降,磁阻曲线证明了反弱局域化的存在。通过对三元合金薄膜在可见光以及近红外光波长范围内的透过率进行研究,发现它在近红外光波长范围内的透过率线性增加,这为三元合金薄膜在红外探测器件方面的应用提供了可能。更多还原

【Abstract】 The alloy structures of thin film based on Bi2Se3, Bi2Te3 and Sb2Te3 is not only the most widely used thermoelectric material, but also the strong topological insulator, so it is possible to be the basic material of Dirac solid state quantum application. In this study, we got the single crystal, ternary and quaternary alloy thin films based on Bi2Se3 and Sb2Te3 in vacuum tube furnace by physical vapor deposition(PVD). Their performance was examined by a series of measurements. The research mainly focuses on the electrical transport properties of the quaternary alloy thin films and the photoelectric properties of ternary alloy thin films. The detailed content and conclusion were described as follows.Firstly, PVD is a useful and simple method to get thin films, we build a system and prepare the Bi2Se3 single crystal thin film, the X-ray diffraction peaks indicated that the c-axis preferred orientation of the film, the SEM image show that there exist triangular spiral domains on the surface, and it indirectly proved its layer structure. The preparation of single thin films provided technical support and comparison for the growth of multi-component alloy thin films.Secondly, we tried to prepare the quaternary alloy thin films(BixSb2-x)( SeyTe3-y) according to the plan we have made. After changing the growth environment and conditions, we successfully got the quaternary alloy thin films at last. Then we systemically studied the structure, surface morphology, composition, electric transport properties and scattering mechanism by X-ray diffraction(XRD), Scanning electron microscope(SEM), X-ray energy dispersive spectroscopy(EDS), Hall effect measurement and Raman spectroscopy. As the increasing value of x and y, the diffraction peak position moved from Sb2Te3 to that of Bi2Se3, the surface roughness became worse, more defects appeared, the carrier concentration decreased, the mobility increased, the peak position of Raman Scattering have a red-shift as a whole. The quaternary alloy thin films have huge potential research value in thermoelectric area.At last, the ternary alloy thin film CaxBi2-xSe3 by doping calcium into Bi2Se3 was got. we found that the main crystal orientation did not change after analyzing its crystal structure and surface morphology. By studying its electric transport properties with Physical property measurement system, we found the carrier conduction type successfully reversed to P-type and the carrier concentration decreased comparing with the Bi2Se3 single thin film, the magnetic resistance curve proved the existence of the weak localization. We measured the transmittance of the ternary alloy thin film in wavelength range of visible light and near-infrared, the increasing linearly transmittance in near-infrared wavelength provided a possibility for the ternary alloy thin film applied in infrared detection.更多还原