人工碳基低维量子结构器件的输运特性研究

With the feature size of the devices keep decreasing, low-dimensional quantum structures of carbon-based materials have attracted extensive attention for the advantageous applications in the field of microelectronics and quantum devices. A possible way to manipulate the tansport properties of devices plays a decisive role in their application. In this project, a series of carbon-based molecular devices will be designed. Effects of configuration, heterojunctions and modification on geometric and electron energy distribution of the devices will be studied using the first principles study. Based on the tradational scattering theory and Green's functional method, the solid state physics theory and quantum chemistry theory are combied, thus, the transport properties of devices can be described accurately. In order to understand the influence of interations between different molecular orbitals on the transport properties, some important key parameters, such as the molecular orbitals distributions, quantum conductances and electron transmission probabilities also will be calculated. To understand how the coupling between the electrodes and edge atoms of molecular have effect on the electronic structure and transport properties, we will designe quantum structure models with different modifications. Furthermore, we will reveal the effect of several passivation type of the dangling bonds on the geometric and electron energy distributions of the devices.In addation, by manipulating the electron energy distribution resonance between the central scattering region and the electrodes, we will clarify the dependencies of transmission probabilities on the size and energy distributions under bias field. The internal mechanism of the transport properties of devices will be revealed. The results will provide the valuable and theoretical basis for the realization of carbon-based low-dimensional quantum devices.

随着器件尺寸的不断小型化，低维量子结构碳材料被认为是微电子学和量子结构器件最有发展前景和潜力的材料之一,控制器件的电输运特性对他们的应用起着决定性作用。本项目通过结构裁剪、构建异质结构和功能化修饰设计碳基分子器件模型，采用第一性原理方法获得稳定的器件构型。在传统散射理论和格林函数基础上将固体物理与量子化学方法相结合，准确描述器件的输运特性。计算器件体系的电子能态分布、电导、透射系数等，弄清不同原子轨道态的相互作用对量子电导的影响以及电极和分子器件的耦合方式和构型与电子输运特性的关联。建立不同分子对量子结构边缘的修饰模型，揭示不同分子或原子对中央散射区修饰的位置和几何分布与电子能态密度分布的关系。通过调控中央散射区的电子能态分布与电极能态的共振分布，阐明外场下器件透射系数对尺寸和能态分布的依赖关系，获得影响器件输运性质的内在机理，为碳基低维量子结构器件的实现提供关键参数和有价值的理论基础。

随着器件尺寸的不断小型化，低维量子结构碳材料被认为是微电子学和量子结构器件领域最有发展前景和潜力的材料之一,控制器件的电输运特性对他们的应用起着决定性作用。本项目通过结构裁剪、构建异质结构和功能化修饰构建并获得了一系列碳基分子器件模型，采用第一性原理方法获得了稳定的器件构型。在传统散射理论和格林函数基础上将固体物理与量子化学方法相结合，准确描述器件的输运特性。研究结果表明，带边功能化修饰对体系弹性和非弹性散射具有明显的影响和调控作用，施主-受主基团的引入使体系的量子化电导有数量级的提高；表面弯曲石墨烯片基分子器件的研究结果表明，随着表面弯曲程度的增大体系的非弹性散射电导明显增大，与弹性散射电导可比拟。弯曲体系的非弹性散射电导比平面体系高出几个数量级。随着源漏电极间距的减小，非弹性散射谱线的幅值峰位出现蓝移。温度对电子的散射过程具有显著地影响，我们主要从电子的热粒子数分布和费米分布两个角度讨论了非弹性隧穿电流的温度效应。从深层机理上研究清楚了器件的电输运机制。此外，系统研究了掺杂吸附共调控及表面原子链线性修饰对低维碳基分子器件的电输运特性的调控。项目的研究结果为实验中确定中央散射区原子类型和构型、分子与电极链接方式提供了有效信息和理论基础。总电流中弹性和非弹性散射电流的比例可能成为实验中测量石墨烯片的局域弯曲程度的有效参考。研究得到的弹性和非弹性散射电流对有限尺寸石墨烯片构型的依赖，使得其在分子探针方面有一定的潜在应用价值。在项目执行期间，合计发表SCI论文9篇，参加国际学术会议两次。