Supported Solid and Liquid Metal Films for Growth of Single-Layer Graphene and Boron Nitride Lateral Heterostructures.

非技术描述：该项目研究了石墨烯和六方氮化硼（h-BN）的生长，以及它们在金属薄膜上的横向异质结构。这两种二维材料都是一个原子厚的晶体，它们的原子排列在蜂窝结构中。它们具有新颖的电子、光子和磁性，可用于下一代技术。单个石墨烯和h-BN微晶的尺寸和形状通过生长条件的变化来操纵，以实现特定应用所需的特性。使用现有微晶的边缘作为用于其它材料的横向生长的一维衬底使得能够形成各种各样的横向异质结构膜，包括石墨烯和h-BN纳米线以及h-BN基质中的石墨烯量子点的交错阵列。该项目培训一名博士生制造和表征这些独特的材料。主要研究者正在与亚利桑那州州立大学的“科学是乐趣”项目合作，为凤凰城地区的K-12学生开发适合年龄的课程模块。技术描述：该项目采用冷壁化学气相沉积（CVD）在薄金属薄膜上生长单层单晶石墨烯和六方氮化硼（h-BN）横向异质结构。调整隔离的石墨烯和h-BN微晶的尺寸和形状，以便使用它们的周边作为其他材料的横向异质外延的衬底。该研究开发了一种能力，能够工程化单层石墨烯/h-BN纳米复合材料，具有受控的形状，尺寸和界面结构（即，Z字形或扶手椅形）并具有所需的性能。石墨烯和h-BN生长在沉积在难熔金属载体上的薄金属膜上，所述难熔金属载体被加热到低于和高于金属膜的熔化温度的温度，以评估CVD在液体金属上用于目标结构生长的功效。研究了各种薄金属和合金膜，以评估它们对石墨烯、h-BN和异质结构形态的影响。在环境扫描电子显微镜的生长过程中的实时成像阐明了生长机制。结合使用冷壁CVD生长的薄膜和异质结构的系统研究，开发了对支撑石墨烯，h-BN和异质结构在固体和液体金属薄膜上生长的基础科学的全面理解。薄膜和异质结构的特点也在原子水平上使用像差校正（扫描）透射电子显微镜。

Non-technical Description: This project investigates the growth of graphene and hexagonal boron nitride (h-BN), as well as their heterostructures in the lateral directions, on thin metal films. Both of these two-dimensional materials are one-atom-thick crystals with their atoms arranged in a honeycomb structure. They have novel electronic, photonic and magnetic properties that can be exploited in next-generation technologies. The size and shape of individual graphene and h-BN crystallites are manipulated through variations in growth conditions to achieve desired properties for specific applications. Using the edges of existing crystallites as one-dimensional substrates for lateral growth of the other material enables formation of a wide variety of laterally heterostructured films including interleaved arrays of graphene and h-BN nanowires and graphene quantum dots in a h-BN matrix. This project trains one PhD student in fabrication and characterization of these unique materials. The principal investigator is collaborating with the "Science is Fun" program at Arizona State University to develop age-appropriate curriculum modules for Phoenix area K-12 students.Technical Description: This project employs cold-wall chemical vapor deposition (CVD) to grow single-layer monocrystalline graphene and hexagonal boron nitride (h-BN) lateral heterostructures onto thin metal films. The size and shape of isolated graphene and h-BN crystallites are tuned in order to use their perimeters as substrates for lateral heteroepitaxy of the other material. The research develops a capability that enables engineering of single-layer graphene/h-BN nanocomposites with controlled shapes, sizes and interface structure (i.e., zigzag or armchair) and with desirable properties. Graphene and h-BN are grown atop thin metal films deposited on refractory metal supports that are heated to temperatures both below and above the metal-film's melting temperature to assess the efficacy of CVD onto liquid metals for growth of the target structures. A variety of thin metal and alloy films are investigated to assess their effects on graphene, h-BN and heterostructure morphology. Real-time imaging during the growth in an environmental scanning electron microscope elucidates growth mechanisms. In combination with systematic investigation of films and heterostructures grown using cold-wall CVD, a comprehensive understanding of the fundamental science underpinning graphene, h-BN and heterostructure growth on both solid and liquid metal films is developed. Films and heterostructures are also characterized at the atomic level using aberration-corrected (scanning) transmission electron microscopy.