全同量子点晶格构筑及其量子态间耦合表征

Since the rapid progress in functional materials, low dimensional lattices tend to be more important in the nano-scale devices. Benefited from their low dimensional effects, a variety of novel and peculiar properties becomes a new focus in the frontier areas. Based on the theoretical simulations and experimental fabrications of Au and Zn quantum dot arrays, this project plans to prepare macro-scale ordered Au and Zu two-dimensional lattices on Si(111)-(7X7) surface by controlling the growth conditions. The fine structures of the two-dimensional lattices will be determined using the RHEED characterization and first-principles simulations. The quantum states in various biases and their spatial distribution in the two-dimensional lattices will be characterized by employing the scanning tunneling microscopy. By combining the first-principles calculations, the local quantum states and their coupling as well as their orbital hybridization will be revealed. Moreover, the dual-probe technique will be used to inject the carriers into the two-dimensional lattices, on which the anisotropic electronic states will be characterized. The transport properties in the two-dimensional lattices will be investigated theoretically, based on which, the coupling behavior between the photons and carriers, as well as its effect on the transport properties of two-dimensional lattices will be revealed.

科学技术的发展促使功能材料和器件日渐趋于小尺度和低维度，而量子点二维晶格以其独特的结构和新奇的效应已成为目前前沿研究热点。本项目基于原理论模拟和实验构筑Au、Zn等原子在Si(111)-(7X7)表面形成全同量子点阵列二维晶格的研究基础，拟进一步制备宏观长程有序的二维晶格，且通过RHEED结构表征和第一性原理计算确定其精细结构。利用扫描隧道显微技术，表征量子点二维晶格的表面形貌、电子态结构及其二维空间分布，了解不同位置的局域量子态信息，结合变偏压电子分波态空间分布的第一性原理计算，认识轨道杂化、量子态间耦合及隧穿效应等对二维晶格电子态的影响，揭示电子态结构的物理起源。进一步，采用双探针表征技术对二维晶格注入载流子，测量各向异性的电子态密度，结合理论模拟，掌握载流子在二维晶格不同对称方向上的输运特性；并研究光子与载流子的光电耦合行为对二维晶格输运特性的影响，揭示新规律。

本项目研究全同量子点二维晶格构筑、量子态耦合，并探索载流子、光子在二维晶格结构中的输运特性。主要研空成果有：1、利用Si(111)-(7X7)周期性表面模板构筑了Au二维晶格，通过结构表征及第一性原理模拟计算，确认了二维晶格的稳定原子构型，揭示其独特宽能隙及量子态耦合等新量子现象；利用有限元分析方法模拟不同偏压的空穴和电子波在Au二维晶格中的空间传播状态，了解载流子在二维晶格不同对称方向上的输运与晶格结构间的关系。同样，在Si(111)-(7X7)周期性表面制备Zn二维晶格，表征其载流子输运特性并比较与Au 二维晶格载流子输运特性的区别。2、采用金属有机物气相外延方法生长AlN/GaN二维超晶格，设计了新型窄带日盲光电探测结构材料，实现了对深紫外光波段不同波长的窄带光电探测，并获得更高的光电流和量子效率。研究通过本项研究，深入了解二维晶格的原子结构、量子耦合特性及载流子、光子输运特性，拓展其在电子和光电子领域中的应用。3、成功研制且搭建了超低温强磁场扫描隧道显微（STM）系统；其最大磁场可达11T，最低温度可降至350mk，为今后更深入研究低温强磁场对二维晶格结构及输运特性奠定基础。相关研究成果先后在Nanoscale、Scientific Reports等重要学术刊物发表论文16篇；申请国家发明专利4项，其中获授权3项；应邀在学术会议上做特邀报5个；培养研究生21人，其中博士生5人。