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Investigation of non-equilibrium phonon populations in biased metallic single-walled carbon nanotubes (SWCNTs)

偏压金属单壁碳纳米管 (SWCNT) 中非平衡声子群的研究

基本信息

批准号：
85215188
负责人：
Professor Dr. Ralph Krupke, Ph.D., since 10/2013
金额：
--
依托单位：
Institut für Nanotechnologie (INT)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2009
资助国家：
德国
起止时间：
2008-12-31 至 2013-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/85215188?language=en
关键词：
Investigation non equilibrium phonon populations

项目摘要

The generation of so called hot-phonons in biased metallic single-walled carbon nanotubes will be experimentally explored. The influence of electron-phonon coupling on the resistance of metallic single-walled carbon nanotubes is relevant to high-current applications such as interconnectors. In the regime of high-bias, accelerated electrons in metallic nanotubes relax under the emission of high-energy phonons. These phonons will accumulate in the nanotube if their generation rate exceeds their relaxation rate. Under these conditions, the increase in population can be detected by Raman spectroscopy where the spectrum will show an increase in the intensity of a particular mode in the high energy region. Using Bose-Einstein statistics one can then calculate the phonontemperature of these phonons. An unresolved and important issue of hot-phonons generation concerns the spatial distribution of the phonons along the single-walled carbon nanotube. In this project we attempt to answer the following questions: (i) Is the generation of the non-equilibrium phonons a local effect? (ii) Must the tube be suspended to reach the predicted phonon-temperature of a few thousand Kelvin and (iii) Does the signal in the high-energy part of the spectrum (anti-Stokes signal) arise from freely suspended tube-segments or from the entire tube length?For the experiment we propose to use Near-field Raman spectroscopy and far-field Raman microscopy operating in a slit-limited-aperture mode, which provide the required spatial resolution of less than 50 nm, in combination with a nanotube specific electron transport measurement setup.

将通过实验探索在偏置金属单壁碳纳米管中产生所谓的热声子。电子声子耦合对金属单壁碳纳米管电阻的影响与互连器等高电流应用有关。在高偏压状态下，金属纳米管中加速的电子在高能声子的发射下弛豫。如果这些声子的产生速率超过其弛豫速率，它们就会在纳米管中积聚。在这些条件下，可以通过拉曼光谱检测到人口的增加，其中光谱将显示高能区域中特定模式的强度增加。使用玻色-爱因斯坦统计数据，我们可以计算这些声子的声子温度。热声子产生的一个未解决的重要问题涉及声子沿单壁碳纳米管的空间分布。在这个项目中，我们试图回答以下问题：（i）非平衡声子的产生是局部效应吗？ (ii) 管必须悬挂才能达到几千开尔文的预测声子温度，以及 (iii) 光谱高能部分的信号（反斯托克斯信号）是否来自自由悬挂的管段或整个管长度？对于实验，我们建议使用在狭缝有限孔径中操作的近场拉曼光谱和远场拉曼显微镜模式，结合纳米管特定的电子传输测量装置，提供所需的小于 50 nm 的空间分辨率。