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Characterization on near-surface electronic properties and investigation of electron transport mechanisms in InAs nanostructures studied by nano-probes

纳米探针研究的 InAs 纳米结构的近表面电子特性表征和电子传输机制研究

基本信息

批准号：
13650024
负责人：
TAKAHASHI Takuji
金额：
$ 0.9万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

We fabricated InAs wire structures and thin films on GaAs giant steps formed on GaAs (110) vicinal substrates as well as InAs self-assemble quantum dot structures on GaAs (001) substrates, and characterized them by means of nano-probe methods such as laser-illuminated STM and conductive tip AFM systems. First, in the laser-illuminated STM, we measured the photo-response on the differential conductance by the superposing the small ac bias to the dc bias under the height control condition from the tunneling current, and we succeeded in visualizing the InAs wire regions in the photo-response images of the differential conductance. Similarly in the current measurements by the conductive tip AFM under the laser illumination, we observed the photo-current enhancement on the InAs regions and the modulation of the capacitive coupling strength between the tip and the sample separated by the surface depletion layers due to the photo-carriers, which informed us the photoabsorption properties and … More the near-surface band diagrams on the single nanostructures. Secondly, we introduced the non-contact mode Kelvin probe force microscopy (KFM) operated in high vacuum, in which the surface potential could be determined from the electrostatic force working between the tip and the sample surface, and we pointed out the importance of the reduction in both the mechanical vibration amplitude of the KFM cantilever as well and the average separation between the tip and the sample to improve the reliability in the potential determination from the two-dimensional theoretical simulations and as well as the experiments. Then we measured the surface potential on the InAs self-assembled quantum dots, showing the dot size dependence of the surface potential, which could be attributed to the carrier accumulation near the InAs surfaces. Finally, we developed the novel method for the quantitative detection of the local current in the very fine structures like InAs wires by using the magnetic force microscopy (MFM), and successfully demonstrated the ac current detection below several ten nA. Less

我们在GaAs（110）衬底上形成的GaAs巨型台阶上制备了InAs线结构和薄膜，在GaAs（001）衬底上制备了InAs自组装量子点结构，并利用激光照射STM和导电尖端AFM系统等纳米探针方法对其进行了表征。首先，在激光照射的STM中，在隧道电流的高度控制条件下，通过将小的交流偏压叠加到直流偏压上，我们测量了差分电导的光响应，并成功地在差分电导的光响应图像中显示了InAs导线区域。同样，在激光照射下的导电针尖AFM电流测量中，我们观察到InAs区域上的光电流增强，以及由于光载流子的存在，针尖与被表面耗尽层分隔的样品之间的电容耦合强度发生了调制，这说明了单纳米结构的光吸收特性和近表面带图。其次，我们介绍了在高真空下工作的非接触模式开尔文探针力显微镜（KFM），在这种显微镜下，表面电位可以通过针尖与样品表面之间的静电力来确定；并指出减小KFM悬臂梁的机械振动幅值以及尖端与样品之间的平均间距对于提高二维理论模拟和实验中电位测定的可靠性的重要性。然后，我们测量了InAs自组装量子点上的表面电位，显示了表面电位与点尺寸的依赖关系，这可能归因于InAs表面附近的载流子堆积。最后，我们开发了一种利用磁力显微镜（MFM）定量检测InAs线等非常精细结构中的局部电流的新方法，并成功地演示了几十nA以下的交流电流检测。少