缺陷与掺杂调制碳纳米管载流子迁移率的理论模拟

The quantum chemistry calculations currently have been widely used in the studies of the low-dimensional materials such as the carbon nanotubes (CNTs). However, few understandings and investigations about the charge carrier mobility of the CNTs influenced or modulated by the defects or dopings are now available from first-principle viewpoint. And the type and the mobility of the charge carrier would directly affect the speed and efficiency of the nano-scaled devices. In this project, the CNTs containing defects or doping atoms are studied by means of the quantum chemistry calculations using the self-consistent-field crystal orbital method. Base on these results, the mobility for different charge carriers of the tubes are then simulated under the framework of condensed-matter physics. The relationship of structure and charge carrier mobility for the CNTs with defects or doping atoms is explored at the atomic level. Furthermore, the influences, modulations and inner mechanics of the charge carrier transport properties by the connect models, chiral edges, dimensionality and quantum sizes for the CNTs with defects or doping atoms are discussed. The new phenomena, new effect and new rules discovered in the studies are also summarized and analyzed in details. These investigations are carried out at the cross points of chemistry, physics, materials science and nanoelectronics, and would provide theoretical basis for the construction and synthesis new low-dimensional carbon-based materials and their applications. The studies are also helpful for the promotion of the scientific and technical developments of the minority regions in the western China.

目前量子化学计算已经广泛用于碳纳米管等低维材料的研究，但仍缺少从第一性原理角度出发理解和探讨缺陷与掺杂对碳纳米管的载流子迁移率的影响和调控。而载流子的类型和迁移率的大小直接影响纳米器件工作的速度和效率。本项目使用基于自洽场晶体轨道法的量子化学计算对含有缺陷或掺杂原子的碳纳米管进行研究。在此基础上基于凝聚态物理理论进一步模拟其不同类型载流子的迁移率。从原子水平上揭示含有缺陷和掺杂原子的碳纳米管的结构与载流子迁移率的联系。探讨在维数受限和尺度受限条件下，键连结构、边缘手性、空间维数和量子尺寸效应对含有缺陷和掺杂原子的碳纳米管的载流子输运性质的影响因素和调控规律及内在机制，并对可能出现的新现象、新效应和新规律进行总结和分析。本项目在化学、物理学、材料科学以及纳米电子学多学科交叉点上开展研究，为构筑合成新型低维碳材料及其应用提供理论依据，推动西部民族地区科技进步。

研究缺陷与掺杂对碳纳米管载流子输运的影响具有重要意义。本项目基于密度泛函理论研究了Si、N、BN等掺杂原子以及Stone–Wales (SW)、单空位和双空位等缺陷对碳纳米管载流子传输性质的影响，考察影响载流子迁移率的主要因素，获得不同因素对载流子传输性质的影响和调控规律。长期以来传统的观点认为，材料中的缺陷与掺杂一般会阻碍载流子运动，使得载流子运动变慢，降低迁移率和材料的输运性能。然而，我们的研究发现一些碳纳米管中特殊缺陷和掺杂会异常地使得碳纳米管的载流子迁移率增加，从而提升材料的载流子输运性能。这是非常特殊的低维固体的量子限域效应的新发现。基于晶体轨道分析，我们对该异常行为给出了合理解释。在项目支持下，发表SCI论文16篇，部分论文获得多次引用和正面评价。参加了全国量子化学会议、国际量子化学会议等国内外学术会议，交流研讨项目成果。研究团队中项目负责人入选宁夏回族自治区首批青年科技人才托举工程，成员中1人晋升讲师职称，培养毕业硕士研究生2人，联合培养博士研究生1人，在读硕士生3人。本项目实施和完成对于我国西部民族地区，尤其宁夏本地区创新人才培养、基础研究、新材料研发创新及区域可持续性发展发挥了应有的作用。