Nucleation and Growth of Epitaxial Graphene Formed by Physical Vapor Deposition

技术：本项目是关于固体源分子束外延(MBE)形成的单层石墨烯和基于石墨烯的异质结构的生长和性质的研究。分子束外延能够很好地控制碳沉积速率，使薄膜能够在广泛的动力学条件下生长，同时消除了与碳前体化学相关的影响，这些影响自然存在于常用的化学气相沉积过程中。这项研究的灵感来自于最近对铜箔上生长的石墨烯的研究，这些研究表明，石墨烯岛核是在该系统中实现原始石墨烯的最终瓶颈。该项目在这些结果的基础上，调查了导致可控石墨烯成核的条件，并探索了石墨烯边缘原子和衬底吸附原子之间的关键相互作用，这在岛屿演化中发挥了关键作用。利用低能电子显微镜在不同衬底上生长石墨烯的实验有望从根本上深入了解衬底织构、晶格失配、衬底阶跃流动和界面相互作用的作用。此外，分子束外延将用于在超高真空条件下形成石墨烯-介电双层膜，将通过电学、结构和光学测量对其进行进一步研究。非技术性：该项目解决了材料科学中具有高度技术相关性的热门领域的基础研究问题。分子束外延技术在石墨烯生长中的应用，将这种先进的沉积技术的广泛能力带入了石墨烯科学和技术的范畴。如果该项目成功，通过在石墨烯和其他材料之间形成原始的界面，可以产生新的功能和增强的性能。教育计划与研究相结合，将来自不同层次的高等教育、社区学院到研究生院的新兴学者聚集在一起，研究石墨烯。外展项目活动的重点是将原创研究概念融入到本科生和社区大学生的暑期体验中，这些学生来自传统上代表人数较少的科学和工程群体。夏季对石墨烯的研究将作为实验室教学模块的试验台，这些模块将在高级、顶尖的实验室课程中实施。

Technical: This project is on the growth and properties of monolayer graphene and graphene based heterostructures formed by solid-source molecular beam epitaxy (MBE). The well-controlled carbon deposition rates made possible by MBE enable the growth of films under a wide range of kinetic conditions while removing effects related to carbon precursor chemistry, which exist naturally in the commonly used chemical vapor deposition processes. The research is inspired by recent studies of graphene grown on copper foils, which show graphene island nucleation as the ultimate bottleneck to achieving pristine graphene in this system. The project, building on these results, investigates the conditions that lead to controlled graphene nucleation and probes the critical interactions between graphene edge atoms and substrate adatoms, which play a key role in island evolution. Experiments of graphene growth on different substrates by low-energy electron microscopy is expected to provide fundamental insight into the roles of substrate texture, lattice mismatch, substrate stepflow, and interfacial interactions. In addition, MBE will be used to form graphene-dielectric bilayers under ultrahigh vacuum conditions, which will be studied further via electrical, structural and optical measurements.Nontechnical: The project addresses basic research issues in a topical area of materials science with high technological relevance. The application of molecular beam epitaxy to graphene growth brings the extensive capabilities of this advanced deposition technique into the fold of graphene science and technology. If the project is successful, new functionalities and enhanced properties can emerge through the formation of pristine interfaces between graphene and other materials. An education plan is integrated with the research and brings together emerging scholars from across different levels of higher education, community college to graduate school, for the study of graphene. Outreach project activities center on the integration of original research concepts into summer experiences for undergraduates and community college students from traditionally underrepresented groups in science and engineering. Summer investigations on graphene will serve as test beds for lab instructional modules that will be implemented in a senior-level, capstone laboratory course.