石墨烯量子点受限结构的量子态研究

With the sizes of the semiconductor transistors approaching the molecular scale, quantum effects become a formidable physical limit facing semiconductor devices. Fortunately, using graphene quantum dots to design quantum nanoelectric devices should be a novel method to overcome this limit. Graphene quantum dots, as the basic functional unit in designing graphene quantum devices, are becoming the research focus of many research fields at home and abroad. However, most of the properties of graphene quantum dots are determined by the quantum states of quantum dots in essence. Therefore, in this project we mainly carry out the following researches on the graphene quantum-dot system: The quantum states of small-size graphene flake quantum dots and the confined graphene quantum dots formed in large-size graphene, as well as the influences of the shapes and boundaries on the quantum states of the quantum dots; The influences of the variations of the quantum-dot size on the quantum states; The quantum states of many quantum-dot systems in single-layer or multiple-layer graphene, the mechanism of how the interdot couplings and the interlayer couplings affect the quantum states, and the approaches to manipulate the interdot and interlayer couplings.This research will be helpful in understanding the graphene quantum-dot states and the manipulation on them, as well as the different properties of graphene quantum dots. This work will not only be of important and fundamental scientific significance, but also provide theoretical basis for the designing and fabricating the new types of nanometer quantum devices in the future.

随着半导体晶体管尺度减小到分子尺度，量子效应将使半导体器件面临不可逾越的物理极限，而应用石墨烯量子点设计量子纳电子器件是克服这种限制的一种新方法。石墨烯量子点作为设计石墨烯量子器件的一种基本功能单元，已逐渐成为国内外科学家关注的热点。考虑到石墨烯量子点的各种性质归根到底是由量子点的量子态决定的，因此，本项目将针对石墨烯量子点系统的量子态重点开展以下研究工作：研究小尺度片状石墨烯量子点和大尺度石墨烯中受限形成的量子点的量子态，考虑形状、边界等对量子点量子态的影响；研究尺度变化对量子点量子态的影响；研究单层和多层石墨烯中多量子点系统的量子态，探索点间耦合和层间耦合对量子态的影响机理以及调控点间耦合和层间耦合的方法等。本研究将加深人们对石墨烯量子点量子态及其调控等的认识，有利于更加全面地理解石墨烯量子点的各种性质。这不仅具有重要的基础科学意义，而且也为未来设计和制造新型纳米量子器件提供理论依据。

随着半导体晶体管尺度减小到分子尺度，量子效应将使半导体器件面临不可逾越的物理极限。研究各种新型量子受限结构如量子点等系统中的量子态及其调控，探索适用于研究量子受限结构各种性质的理论方法，具有重要的应用价值和科学意义。基于此，本项目利用紧束缚方法研究了单量子点、多量子点的能级，并考虑了尺寸、形状、边界、层数等对量子点量子态的影响，进一步考虑了电场、衬底的调控作用，有利于更加全面地理解石墨烯量子点的各种性质。基于石墨烯的研究经验，将研究推进到到各向异性的黑磷系统，研究了块状黑磷、黑磷纳米带、黑磷量子点的性质，考虑了电场、磁场、应力等的影响。通过对各向异性的黑磷和各向同性的石墨烯的比较，从而把受限量子结构的研究提高到更高的水平。另外，基于第一性原理计算开展了材料能带、发光谱等的研究。因此，本项目也为结合紧束缚方法和第一性原理计算等方法，进而开展原创性的研究工作奠定了理论基础。