Potential of Graphene as a Universal Substrate for Disruptive Epitaxial Devices

石墨烯的二维（2D）碳结构独特地结合了机械灵活性、弱表面键合和六边形晶格。当半导体晶体在石墨烯上生长时，其二维薄片有望弹性地重塑以适应晶体或热不匹配，从而在任意衬底上生长高质量的半导体，而不会产生晶体变形和损伤。这是目前社区中激烈研究的主题，但由于还没有找到可行的解决方案，这个问题仍然没有解决。在石墨烯晶体生长的初始阶段，许多观察到的效应是令人惊讶的，仍然没有完全理解。高性能半导体器件是通过在兼容衬底上生长特殊的、薄的、高质量的“外延”层而制成的。然而，这些基板价格昂贵，而且来自有限的全球资源，这往往限制了将具有互补特性的材料集成的可能性。在今天的市场中，性能期望达到前所未有的水平，迫使行业设计和生产基于完全不同的晶体结构堆栈的器件，这是传统上在外延中禁止的条件。应对这一挑战所需的科学技术仍有待充分发展，而能够适应这些极端条件的新型基质的创造是一条有希望的途径。然而，由于这些特殊的基板推高了器件成本并限制了其功能，任何可能有希望进入市场的解决方案都必须具有成本效益和可扩展性。这一挑战引发了一个问题：“石墨烯是解决错配外延基本挑战的最终材料吗？”***我的研究项目将把一个多方面的、高潜力的材料（石墨烯）与一个基础的工业和科学挑战结合起来，产生影响。我将通过原创和创新的方法具体解决石墨烯上III-V生长的两个主要问题：通过我称之为“锚点成核”的成核过程，工程石墨烯的表面能来增强石墨烯上III-V材料的成核。***这将涉及学生和研究人员的工作，阐明三维晶体（GaAs, InP, GaN）在二维晶体（即石墨烯）上的成核和生长的物理原理。这里的潜力是巨大的，为新一代混合器件提供外延和半导体转移到任意衬底（例如：金属，陶瓷，柔性聚合物），如低重量，柔性高效太阳能电池，以及在Si上集成III-V器件，实现与高速电子和光子学的兼容性。此次活动的重点将是高效太阳能电池的实际演示结果。

Graphene's two dimensional (2D) carbon structure uniquely combines mechanical flexibility, weak surface bonding and a hexagonal lattice. When semiconductor crystals are grown onto graphene, its 2D sheet is expected to elastically reshape to accommodate crystal or thermal mismatches, enabling growth of high-quality semiconductors on arbitrary substrates, without crystal deformations and impairments. This is currently the subject of intense research in the community, but the question remains open as no viable solution was reached yet. Many of the observed effects during the initial phase of the crystal growth on graphene are surprising and still not fully understood.***High performance semiconductor devices are made by growing special, thin, high quality “epitaxy” layers onto compatible substrates. However the substrates are costly and come from limited global resources, which often limit the possibility of integrating materials with complementary properties. ***In today's market, the performance expectations are reaching unprecedented levels that force the industry to design and produce devices based on stack of radically different crystal structures, a condition traditionally forbidden in epitaxy. The science and technology necessary to face this challenge remains to be fully developed, and the creation of new kinds of substrates, with the ability to accommodate these extreme conditions is a promising avenue. However, since these special substrates drive up device cost and limits its functionalities, any solution that might have hope to access the market must be cost-effective and scalable. This challenge motivated the question: “Is graphene the ultimate material to solve fundamental challenges of mismatched epitaxy?” ***My research program will bring together a multifaceted, high potential material (graphene) with a fundamental industrial and scientific challenge, to generate impact. I will specifically address the two main issues in III-V growth on graphene through original and innovative approache: engineer graphene's surface energy to enhance the nucleation of III-Vs materials on graphene through a nucleation process that I name “Anchor Point Nucleation”.***This will involve students and researchers in work illuminating the physics of nucleation and growth for 3D crystals (GaAs, InP, GaN) onto 2D crystals (i.e: graphene). The potential here is vast, offering epitaxy and transfer of semiconductors onto arbitrary substrates (e.g: metals, ceramics, flexible polymers) for new generations of hybrid devices such as low-weight, flexible high-efficiency solar cells, and integration of III-V devices on Si, enabling compatibility with high speed electronics and photonics. A focus of the activity will be outcomes involving practical demonstrations on high-efficiency solar cells.