含褶皱石墨烯纳米条带的输运性能研究

发布时间：2018-04-26 09:09

本文选题：石墨烯 + 褶皱　；参考：《南京邮电大学》2015年硕士论文

【摘要】：石墨烯是由碳原子组成的二维单原子层材料,其发现打破了二维晶体在一定温度下无法稳定存在这一观点。但石墨烯并非绝对理想的二维晶体,研究表明石墨烯在垂直其平面方向存在很多起伏,这些褶皱起伏可能是石墨烯稳定存在的根本原因。同时,它对石墨烯的各方面性质起着重要的影响。应用非平衡格林函数方法,我们计算了含褶皱石墨烯纳米条带的输运性能,研究分析了含褶皱石墨烯纳米条带褶皱特性对电子输运性能的影响。我们对两种不同情况进行了研究:电流方向平行褶皱方向和电流方向垂直褶皱方向。这两种情形我们又分别研究了zigzag型和armchair型这两种不同边缘结构的石墨烯纳米带。对于不同宽度W的石墨烯条带,我们首先保持褶皱周期N不变,通过改变褶皱振幅A分析了褶皱振幅的变化对石墨烯条带的电导特性的影响;然后保持褶皱A不变,分析了褶皱周期N的变化对石墨烯条带的电导特性的影响;进而系统研究了不同褶皱周期N,不同褶皱起伏度A,不同石墨烯条带宽度W等因素对石墨烯条带输运性能的影响。研究表明,对于第一种情况,不管是zigzag型还是armchair型石墨烯,其电导不再展现严格的量子化台阶,而是在原有台阶上表现出微小的振荡,我们认为这是由于褶皱相关的应力变化所引起的。对于第二种情形,zigzag型石墨烯条带的量子电导平台整体上呈现出先增加再降低的趋势,而armchair型石墨烯条带的导电性在金属性和半导体型之间转换,具体的影响机制,我们还在进一步的研究之中。
[Abstract]:Graphene is a two-dimensional monatomic material composed of carbon atoms. Its discovery breaks the idea that two-dimensional crystals can not exist stably at a certain temperature. But graphene is not an absolute ideal two-dimensional crystal. It is shown that there are many fluctuations in graphene perpendicular to its plane, which may be the fundamental reason for the existence of graphene stability. At the same time, it plays an important role in the properties of graphene. Using the non-equilibrium Green's function method, we have calculated the transport properties of graphene nanostrip containing folds, and studied the effect of folding characteristics on the electron transport properties of the nanostrip containing folded graphene. We study two different cases: the current direction is parallel to the fold direction and the current direction is perpendicular to the fold direction. In these two cases, the graphene nanobelts with different edge structures, zigzag type and armchair type, are studied respectively. For graphene bands of different widths, we first keep the folding period N constant. By changing the fold amplitude A, we analyze the influence of the fold amplitude on the conductivity of graphene bands, and then keep the fold A unchanged. The influence of the variation of folding period N on the conductivity of graphene strip was analyzed, and the effects of different folding period N, different fold fluctuation degree A and different width of graphene strip on the transport properties of graphene strip were studied systematically. Studies have shown that in the first case, whether zigzag or armchair graphene, its conductance does not exhibit strictly quantized steps, but shows tiny oscillations on the original steps. We believe that this is due to changes in the stress associated with folds. For the second case, the quantum conductance platform of the zigzag type graphene strip shows a tendency of increasing first and then decreasing, while the conductivity of the armchair type graphene strip transforms between the gold attribute and the semiconductor type. We are still in the process of further study.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;TB383.1

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