石墨烯结构量子点的自旋电子态调制机理及自旋输运特性研究

Quantum dots (QD) structure is the key component in the nanoelectronic devices. Graphene is the promising material to be served as the novel controllable QD structure owing to its high charge mobility and long time spin relaxation and the possibility for tailoring the nanostructure in high precision. We propose the QD nanoconstructured model in terms of the graphene nanomaterials according to the latest experimental investigations, taking the influences of rippling disorder on the interactions between the QD and the electrodes as well as edge disorder on the deposition position of the nanomaterial and electronic structures into account. We will make use of quantum electronic structure model combined with non-equilibrium Green's function and are dedicated to further develop this method to simulate the spin-dependent electronic states as well as spin-dependent electron transport characteristics of the stable QD structure in nanoscale with better precision. This project has been concentrated on establishing parameter system to effectively control the performance of spin-dependent electronic properties of the nanodevices by the stable structure in nanoscale and external field and other related factors. More importantly, this project is focused on the comprehensive understanding of physical mechanism for the influences of mechanical transformation and molecule adsorption on the specific structure in micro-nanoscale and spin-dependent electronic states and spin-dependent transport properties of the graphene-based QD. Our theoretical investigations are expected to lead to the establishment of the parameter system related to the spin-dependent electronic transport that can be sensitive to the tiny change in the graphene-based QD, which is also crucial to the building of graphene-based QD detector/sensor and able to provide the theoretical fundamentals as well as designing plans.

量子点结构是纳米电子器件的核心构件，石墨烯以其高温下的高电子迁移率、长时间的自旋弛豫、更佳的裁剪特性等特点成为制备新型可控量子点结构的理想材料。本项目根据当前理论与实验研究结果提出基于石墨烯材料的量子点结构模型，充分考虑起伏性无序对量子点与电极之间相互作用的物理机制和边缘缺陷对材料的沉积位置、体系的电子结构及输运特性的影响。采用量子电子结构模型与非平衡格林函数相结合的方法进一步发展对具有稳定纳米尺度结构量子点器件自旋电子态及自旋相关输运特性的预测，探索建立纳米尺度稳定结构、外场等参数控制体系，以有效调控石墨烯结构量子点的自旋相关电学性能。研究机械形变和分子吸附对量子点微纳尺度结构、自旋电子态和自旋相关输运特性的影响的内在机理，进而确立自旋电子输运特性相关的敏感参数控制体系准确地响应石墨烯量子点纳米尺度结构的微变化，为将来石墨烯量子点探测器/传感器与纳米电子器件的制造与应用提供理论参考。

石墨烯以其高温下的高电子迁移率、长时间的自旋弛豫、更佳的裁剪特性等特点成为制备新型可控量子点结构的理想材料。本项目根据当前理论与实验研究结果提出基于石墨烯材料的量子点结构模型，考虑无序和缺陷结构对石墨烯量子点的的电子结构及电子输运特性的影响的物理机制。采用量子电子结构模型与非平衡格林函数相结合的方法，对外场下石墨烯量子点器件的自旋相关电子输运特性进行模拟仿真并得到电压-电流响应关系，进一步发展对具有稳定纳米尺度结构量子点器件自旋相关输运特性的预测。研究了不同的缺陷结构和异质原子掺杂来调控量子点的自旋输运性能和提高材料的化学活性，发现随着硫原子掺杂浓度的增加，石墨烯量子点呈现金属性增强和直接-间接带隙的转变，光异构化使得体系可以储存能量。研究发现具有不同对称性的SW缺陷可以提高或降低石墨烯结构的输运性能。研究纳米尺度稳定结构、外场等参数控制体系有效调控石墨烯结构量子点的自旋相关电学性能。磁性原子掺杂结合双原子空位缺陷复合结构对石墨烯量子点的结构修饰可以调制体系的电子能带结构成为半金属。研究发现二维锗烷纳米材料中的单氢脱附确实可以引入局域在锗原子上的磁矩，赋予了材料铁磁性；氢原子脱附和锗原子掺杂分别引起吸收系数的红移和蓝移。研究表明可以根据锗烷纳米带的宽度来调控量子受限程度，进而可以采用控制样品宽度的方法来调控材料的能隙及电子输运，且二维锗烷材料具有各项异性的电子输运特性。探索了多空位缺陷对锗烷纳米带自旋电子学性质的影响，发现脱附掉氢原子的锗原子经过弛豫后更倾向于具有非磁的结构。预测并设计具有较大体能隙的砷二维材料拓扑绝缘体，自旋轨道耦合都能够打开一个非平庸的能隙。功能化使得砷二维材料具有本征的非平庸电子结构特性，赋予其更大的实际应用价值。最后，建立自旋输运特性相关的敏感参数体系响应二维纳米材料的微尺度变化，为将来石墨烯和锗烯在纳米电子器件和能量存储领域应用提供理论参考。