Mechanisms of Decoupling Graphene from Strong-Binding Substrates by Intercalation

这项资助的目的是通过模拟和实验相结合的方法，阐明石墨烯与各种衬底的电子相互作用以及解耦底层生长的生长过程。石墨烯是一种单层碳原子，即使在室温下也表现出微米级的无耗散导电性能。为了在基于石墨烯的纳米器件方面取得真正突破性的进展，必须在绝缘衬底上生长大而无缺陷的石墨烯薄片。虽然碳化硅外延生长的石墨烯对未来的纳米电子学特别有吸引力，但这种方法有一个严重的缺陷。第一层石墨烯虽然容易均匀生长，但不导电；从电子学的角度来看，这一层根本不是石墨烯，而是一种“缓冲层”。在这个方案中，氧插层将被用作一种将石墨烯从碳化硅表面解偶联的方法。导致完全解耦的石墨烯层或缺陷/氧化的石墨烯形成的条件不仅取决于原子尺度的过程，而且取决于数百纳米距离上的表面特征的相互作用。为了应对这一挑战，我们提出了一种多尺度的方法，将原位表面表征的实验技术与原子尺度的计算、表面结构的随机方法和动力学蒙特卡罗方法相结合，如果成功，这项工作将导致一种新的方法来生长大面积石墨烯，通过光刻图案化可以制造低功耗的纳米电子器件。我们提出的去耦合石墨烯的方法实现简单，可以在预制器件上进行，即在适当的位置进行金属接触，并与传统的互补金属氧化物半导体工艺兼容；因此，它引起了半导体行业的极大兴趣。这笔拨款将为研究生和本科生提供机会，让他们在领先的工业实验室开展实验工作，并发展高级计算和建模技能。在建模方法方面取得的进步将包括在PI为促进动手模拟体验而创建的课程中。

The goal of this grant is to elucidate the electronic interaction of graphene with various substrates and the growth process of decoupling underlayer growth through a combined modeling and experimental approach. Graphene, a single-layer of carbon atoms, exhibits dissipation-free electric conduction over the scale of microns even at room temperature. To enable truly groundbreaking advances in graphene-based nanodevices, large and defect-free graphene sheets must be grown on insulating substrates. While graphene grown epitaxially on silicon carbide is particularly attractive for future nanoelectronics, this method has a serious drawback. The first graphene layer, while easy to grow uniformly, is nonconductive; from an electronic point of view, this layer is not graphene at all, but rather a "buffer layer." In this proposal, oxygen intercalation will be used as a means to decouple graphene from the SiC surface. Conditions that lead to a perfectly decoupled graphene layer or alternatively the formation of defective/oxidized graphene depend not only on atomic-scale processes, but also on interactions of surface features over distances of hundreds of nanometers. In order to address this challenge, we propose a multi-scale approach that combines experimental techniques for in situ surface characterization with atomic-scale calculations, stochastic methods for finding surface structures, and kinetic Monte Carlo methods.If successful, this work will lead to a novel approach to grow large area graphene, which through lithographic patterning can be used to fabricate low-power nanoelectronic devices. The method of decoupling graphene we propose is simple to implement, can be carried out on prefabricated devices i.e., with metal contacts in place, and is compatible with conventional complementary metal-oxide semiconductor processes; it is therefore of great interest to the semiconductor industry. The grant will provide an opportunity for graduate and undergraduate students to both carry out experimental work at a leading industrial lab and to develop advanced computational and modeling skills. The progress made in the modeling methods will be included in the courses that the PI has created to promote hands-on simulation experience.