Electronic Fluctuation and Localization at Point Defects

技术：这个单一研究者研究计划系统地调查与单点缺陷相关的输运现象。与点缺陷相关的电子散射、局部化和波动最终限制了电子器件的实际实现，而工业设计和制造更小尺度电子电路的能力受到对这些点缺陷的控制的限制。虽然这些主题在理论上已经得到了广泛的研究，但很少有实验平台可用于直接测量。在本项目中，实验平台由单壁碳纳米管的一维传导组成。在这个一维极限中，单键的改变足以显著地改变电子行为，为原子尺度效应变得可测量、可区分和可复制的传输机制提供了一个窗口。纳米管电路在缺陷产生之前和之后的测量非常直接地识别了点缺陷和电子效应之间的相互作用，以便绘制出与不同化学终止相关的可复制电子特征。通过使用电导光谱、局部扫描探针技术、噪声光谱、光学光谱和退火过程中的原位表征，本项目旨在完成与纳米尺度物理和半导体工业相关的受控和系统研究。此外，所有的工作将由研究生和本科生在一个训练环境中完成，旨在使初级研究人员接触到与未来科学职业相关的问题和技术。非技术：现代晶体管、存储元件以及连接它们的所有线路在一代又一代产品中不断缩小。在极端情况下，构成这些电路元件的材料薄膜已经只有几个原子厚了。半导体工业预计，在不久的将来，越来越多的器件将跨越这个极限，在这个极限中，成功或失败可能取决于单个原子的偶然存在或不存在。为了预测在这个极限下科学界和工业界会观察到什么样的影响，这个项目制造和测试了有意包含单原子缺陷的电子电路。该实验平台使用的碳纳米管导体只有几个原子宽，直接达到了原子尺度效应可以测量、区分和重现的极限。本科生和研究生接受培训，测试纳米管电路在加入单原子缺陷之前和之后，并识别由此产生的电子变化。这种程度的控制可以系统地研究原子缺陷的电子后果，并通过进一步的化学裁剪，在实际设备中进行校正。结合材料物理学的独特教育计划，该项目为初级研究人员提供了下一代电子器件中迫在眉睫的问题的实践和理论理解，以及解决这些问题的相关技术。

Technical:This single investigator research program systematically investigates transport phenomena associated with single point defects. The electronic scattering, localization, and fluctuation associated with a point defect ultimately limit what is practically achievable in electronics, and industry's ability to design and build electronic circuits at ever smaller scales is limited by control over these sites. While such topics have been extensively treated theoretically, few experimental platforms are available for making direct measurements. In this project, the experimental platform consists of one-dimensional conduction through single-walled carbon nanotubes. In this one-dimensional limit, the alteration of single bonds is sufficient to dramatically alter electronic behavior, providing a window into the transport regime where atomic-scale effects become measurable, distinguishable, and reproducible. The measurement of nanotube circuits both before and after defect creation very directly identifies the interplay between point defects and electronic effects, in order to map out reproducible electronic features associated with different chemical terminations. By using conductance spectroscopy, local scanning probe techniques, noise spectroscopy, optical spectroscopy, and in situ characterization during annealing, this project aims to complete a controlled and systematic study relevant to nanoscale physics and the semiconductor industry. Furthermore, all of the work will be completed by graduate and undergraduate students in a training environment designed to expose junior researchers to problems and techniques relevant to future careers in science.Non-Technical:Modern transistors, memory elements, and all of the wiring that connects them continue to shrink from one generation of products to the next. In extreme cases, the films of material that make up these circuit elements are already only a few atoms thick. The semiconductor industry anticipates that, in the near future, more and more devices will cross into this limit where success or failure can depend on the accidental presence or absence of individual atom. In order to forecast what kinds of effects science and industry will observe in this limit, this project fabricates and tests electronic circuits that intentionally contain single atomic defects. The experimental platform, which uses carbon nanotube conductors only a few atoms wide, directly accesses the limit where atomic scale effects can become measurable, distinguishable, and reproducible. Undergraduate and graduate students are trained to test nanotube circuits before and after the incorporation of single atomic defects, and to identify the electronic changes that result. This degree of control allows the electronic consequences of atomic defects to be systematically investigated and, through further chemical tailoring, corrected for in practical devices. Combined with a unique educational program in Materials Physics, this project provides junior researchers with both practical and theoretical understanding of looming issues in next generation electronic devices, and the relevant techniques for solving them.