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

非技术描述：本项目研究石墨烯和六方氮化硼（h-BN）在金属薄膜上的生长，以及它们在横向上的异质结构。这两种二维材料都是单原子厚度的晶体，其原子排列成蜂窝状结构。它们具有新颖的电子、光子和磁性能，可用于下一代技术。单个石墨烯和氢氮化硼晶体的大小和形状可以通过生长条件的变化来控制，以达到特定应用所需的性能。利用现有晶体的边缘作为其他材料横向生长的一维衬底，可以形成各种各样的横向异质结构薄膜，包括石墨烯和h-BN纳米线的交错阵列和h-BN矩阵中的石墨烯量子点。该项目培养一名博士生在制造和表征这些独特的材料。首席研究员正在与亚利桑那州立大学的“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：本项目采用冷壁化学气相沉积（CVD）技术在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。分离的石墨烯和氢氮化硼晶体的大小和形状被调整，以便利用它们的周长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，使单层石墨烯/h-BN纳米复合材料的工程具有可控的形状，尺寸和界面结构（即之字形或扶手椅），并具有理想的性能。石墨烯和h-BN生长在沉积在难熔金属支架上的金属薄膜上，加热到低于或高于金属薄膜熔化温度的温度，以评估CVD在液态金属上生长目标结构的效果。研究了各种金属薄膜和合金薄膜对石墨烯、氢氮化硼和异质结构形貌的影响。环境扫描电子显微镜下生长过程的实时成像阐明了生长机制。结合对冷壁CVD生长薄膜和异质结构的系统研究，对石墨烯、氢氮化硼和异质结构在固体和液态金属薄膜上生长的基础科学有了全面的了解。薄膜和异质结构也被表征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.