兰州大学机构库 >物理科学与技术学院
单壁碳纳米管拉曼光谱及电输运性质研究
Alternative TitleRaman Spectroscopy and Electron Transport of Single-Walled Carbon Nanotubes
高平奇
Thesis Advisor贺德衍
2010-05-31
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword碳纳米管 拉曼光谱 应力 静电注入 库仑阻塞 场效应管 纳米间距电极 交流电泳
Abstract本论文研究了单壁碳纳米管(SWNTs)的拉曼光谱和电输运特性。 首先,利用共振拉曼光谱研究了SWNTs对几种外界作用的响应。对较大直径超长碳管中反常拉曼光谱的研究发现,沿着碳管轴向特征拉曼光谱G+、G–和G′峰均明显低于文献报道的实验和理论值。显著的拉曼红移归因于内建张应力作用。 在SWNTs场效应管(FETs)工作状态下,原位研究了半导体性及金属性碳管拉曼光谱对外加电场的响应。G–拉曼模在负栅压下向高波数移动并伴随着峰宽的窄化,但对正偏压无响应。随着单位长度SWNTs上电功率消耗的增加,G峰向低波数平移,波形同时逐渐展宽。 其次,用电子束蒸发和快速热退火工艺在SWNT-FETs表面自组装了金纳米颗粒,制备出新奇的SWNT@金纳米颗粒。表面金属纳米颗粒的库仑作用改变了SWNTs的电子结构。当温度低于150 K时,在长约2 µm的导电沟道中观察到强烈的电流振荡。 借助于纳米碳链@SWNT复合结构,首次详细研究了sp杂化的一维碳原子链的拉曼谱和电学特性。纳米碳链@SWNT复合结构具有独特的量子线特性,呈现非线性电学特性,电导随温度的变化遵从幂指数关系,类似于Luttinger流体。 再次,用传统光刻技术结合自对准的方法制备出间距约为5 nm的金属电极,成功制备出大面积纳米间距电极阵列,成功实现了在整个硅片上碳管纳米器件的集成。 最后,用低功函数的金属(Sc, Sm, Al等)作为源、漏电极材料制备了性能稳定的n型SWNT-FETs。所制备的SWNT-FETs的开关电流比大于3个数量级,并且在约5 µm的导电通道中呈现出近似弹道输运的性质,电导约为0.02 G0。
Other AbstractThis thesis presents the main findings in my PhD project on the Raman spectrum and the electron transport properties of single-walled carbon nanotubes (SWNTs). Resonance Raman spectroscopy is firstly used to characterize the structural properties of SWNTs under various external perturbations, including strain, nanoparticles decorated, electrostatic gating, electrical heating, et al. Afterwards, the electron transport mechanisms in two novel SWNTs hybrid structures, SWNT@Au-NCs (gold nanocrystals) and SWNT@Cn (carbon chains), are investigated. At last, stable n-type SWNT field effect transistors (FETs) are successfully fabricated. One conventional optical lithography compatible method is developed for sub-10 nm nanogap electrode arrays fabrication, which has been proven an excellent way for nano-sized devices integration. Abnormal Raman scattering from a large diameter ultralong SWNT is studied in detail. Along the SWNT, the Raman spectra show the frequencies of 1553, 1563, and 2597 cm-1 for G+, G–, and G′ peaks, respectively, much lower than the corresponding frequencies well reported both experimentally and theoretically. The significant downshifts in the peaks frequencies can be attributed to self-built tensile strain which is likely caused by carbon nanodots decorated on the tube. After infrared laser heating is performed to one point of it, all the Raman modes are found to shift to higher frequencies and approach to their conventional values. We suggest that the SWNTs with larger diameters easily possess such self-built strain compared to small-diameter SWNTs because of the weaker curvature effect for the larger ones. In situ Raman measurements have been carried out on a thin bundle of SWNTs in FET configuration at various gate voltages. Two excitation lasers with the photon energy of 1.96 eV and 2.41 eV are selected to excite the Raman scattering modes of metallic and semiconducting SWNTs in the bundle, respectively. For the metallic SWNTs, the G– Raman mode is found to shift to higher frequencies and narrow down its line shape at negative gate voltages, but be insensitive to positive gate voltages. These findings confirm that the Kohn anomaly exists in a thin SWNTs bundle and that the LO phonon mode changes along with the position of the Fermi level in the metallic SWNTs. In contrast, semiconducting SWNTs do not show any observable changes in the Raman spectra. Electrical bias voltages tuned Raman spectroscopic of SWNT-FET show that the G pe...
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Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/230219
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
高平奇. 单壁碳纳米管拉曼光谱及电输运性质研究[D]. 兰州. 兰州大学,2010.
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