Thermo-Mechanical Effects on Electrical Transport in Carbon Nanotubes

碳纳米管电传输的热机械效应

• 批准号: 0501436
• 负责人: Md Haque
• 金额: --
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0501436&HistoricalAwards=false
• 关键词: Thermo; Mechanical; Effects; Electrical; Transport

Carbon nanotubes (mono/multi-layers of carbon atoms rolled into seamless tubes) are known to have superior electrical, mechanical, thermal and chemical properties. Interestingly, the same reasons behind their superiority also make them very sensitive to electrical, mechanical, thermal and chemical fields. Practical applications, as in electronics, sensors and actuators, composites and bio-medical, are likely to involve nanotubes that are mechanically strained and chemically treated during fabrication - and not the pristine ones. The very high power density of such ultraminiaturized devices will cause higher operating temperatures (observed even in the existing computer chips), which will drastically alter the transport properties of the highly confined nanotube electrons. Studies involving the sensitivity of electrical properties under mechanical or thermal fields (such as tuning electrical properties with mechanical displacement or vice versa) have been mostly theoretical. Experimental studies focusing on the simultaneous effects of temperature (300 K) and mechanical force-displacement on the electrical properties of the nanotubes are rare in the literature, an observation that motivates this research proposal.Proposed Activities and their Intellectual Merits: The specific aims of this research are, (i) Development of a micro-electro-mechanical characterization instrument with co-fabricated freestanding single carbon nanotube specimens. The 1mm x 1mm size device will be compatible with any type of microscopy (Optical/SEM/TEM/STM). It will measure force and displacement with 20 pico-Newton and 5 nm resolutions respectively, using an optical microscope. The mechanical sensors (electrically isolated and metallized silicon microbeams) will also work as electrical connectors to measure current-voltage signals. (ii) Study the effects of elevated temperature on the mechanical properties (Young's modulus, fracture stress and strain) of individual carbon nanotubes, in-situ inside the transmission electron microscope. (iii)Study the electrical properties of carbon nanotubes for a wide range of temperature (300-500K) and mechanical strain (up to 30%), for which data is not yet available in the literature. The instrument will allow in-situ atomic resolution experiments on individual carbon nanotubes for simultaneous qualitative (direct visual information on deformation, defect generation and failure of the nanotubes) and quantitative information. The wealth of data on the separate and coupled effects of thermal, mechanical and chemical environmental factors will help researchers gaining insight to the coupling of these fields.Broader Impacts of the Proposed Activities: The experimental data and the fundamental understanding in the coupling of thermal, electrical and mechanical fields will provide better design guidelines for future nanoscale electronics, sensors and novel materials applications. The proposed novel experimental tool will bridge the existing wide gap between theoretical andexperimental studies on nanostructures. Technology transfer of the low cost tool ($25/unit) will promote multi-disciplinary research (such as mechano-biology), wherever high-resolution force and displacement sensing are required. We will train one graduate and one under-represented category undergraduate student (employed through Minority in Engineering program at Penn State) in this cutting-edge research. The research results will be used as a case study in a new technical elective course, which the PI developed to bring nanoscale sensors and actuators, materials science, electronics and electron microscopy in the classroom. We will also train high school teachers in the fundamental aspects of micro and nanotechnology and give their students 'virtual' experience on electron microscopy (web-based remote operation of a scanning electron microscope) to reach out to our future workforce in the each years of this research project.

已知碳纳米管（卷成无缝管的单层/多层碳原子）具有上级电、机械、热和化学性质。有趣的是，其优越性背后的相同原因也使它们对电气，机械，热和化学领域非常敏感。实际应用中，如电子、传感器和执行器、复合材料和生物医学，可能涉及在制造过程中机械应变和化学处理的纳米管-而不是原始的纳米管。这种超小型化设备的非常高的功率密度将导致更高的工作温度（即使在现有的计算机芯片中也可以观察到），这将大大改变高度受限的纳米管电子的传输特性。涉及机械或热场下的电特性的灵敏度的研究（例如用机械位移调谐电特性或反之亦然）大多是理论上的。在文献中，关注温度（300 K）和机械力-位移对纳米管电性能的同时影响的实验研究是罕见的，这一观察结果激发了本研究提案。本研究的具体目标是，（i）开发一种微机电表征仪器，其中包括共同制作的独立式单碳纳米管样品。1 mm x 1 mm尺寸的器械将与任何类型的显微镜（光学/SEM/TEM/STM）兼容。它将使用光学显微镜分别以20皮牛顿和5 nm的分辨率测量力和位移。机械传感器（电隔离和金属化硅微梁）也将作为电连接器工作，以测量电流-电压信号。 (ii)研究高温对单个碳纳米管的机械性能（杨氏模量，断裂应力和应变）的影响，在透射电子显微镜内原位。 （iii）研究碳纳米管在广泛温度（300- 500 K）和机械应变（高达30%）范围内的电性能，这方面的数据尚未在文献中提供。 该仪器将允许对单个碳纳米管进行原位原子分辨率实验，以同时获得定性（关于纳米管变形、缺陷产生和失效的直接视觉信息）和定量信息。丰富的热、力和化学环境因素的单独和耦合效应的数据将有助于研究人员深入了解这些领域的耦合。拟议活动的更广泛影响：实验数据和对热、电和力场耦合的基本理解将为未来的纳米电子、传感器和新材料应用提供更好的设计指导。提出的新的实验工具将弥合现有的理论和实验研究之间的纳米结构的巨大差距。低成本工具（25美元/台）的技术转让将促进多学科研究（如机械生物学），在需要高分辨率力和位移传感的地方。我们将在这项前沿研究中培养一名研究生和一名代表性不足的本科生（通过宾夕法尼亚州立大学工程项目少数民族就业）。研究结果将被用作一个新的技术选修课程，其中PI开发，使纳米传感器和执行器，材料科学，电子和电子显微镜在课堂上的案例研究。我们还将在微观和纳米技术的基本方面培训高中教师，并为学生提供电子显微镜的“虚拟”体验（基于网络的扫描电子显微镜远程操作），以在本研究项目的每一年中接触我们未来的劳动力。