Zulqurnain Muhammad, Burton Oliver J, Al-Hada Mohamed, Goff Lucy E, Hofmann Stephan, Hirst Louise C
Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE United Kingdom.
Cambridge Graphene Centre, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
Nanotechnology. 2022 Sep 8;33(48). doi: 10.1088/1361-6528/ac8a4f.
Remote epitaxy is an emerging materials synthesis technique which employs a 2D interface layer, often graphene, to enable the epitaxial deposition of low defect single crystal films while restricting bonding between the growth layer and the underlying substrate. This allows for the subsequent release of the epitaxial film for integration with other systems and reuse of growth substrates. This approach is applicable to material systems with an ionic component to their bonding, making it notably appealing for III-V alloys, which are a technologically important family of materials. Chemical vapour deposition growth of graphene and wet transfer to a III-V substrate with a polymer handle is a potentially scalable and low cost approach to producing the required growth surface for remote epitaxy of these materials, however, the presence of water promotes the formation of a III-V oxide layer, which degrades the quality of subsequently grown epitaxial films. This work demonstrates the use of an argon ion beam for the controlled introduction of defects in a monolayer graphene interface layer to enable the growth of a single crystal GaAs film by molecular beam epitaxy, despite the presence of a native oxide at the substrate/graphene interface. A hybrid mechanism of defect seeded lateral overgrowth with remote epitaxy contributing the coalescence of the film is indicated. The exfoliation of the GaAs films reveals the presence of defect seeded nucleation sites, highlighting the need to balance the benefits of defect seeding on crystal quality against the requirement for subsequent exfoliation of the film, for future large area development of this approach.
远程外延是一种新兴的材料合成技术，它采用二维界面层（通常是石墨烯），在限制生长层与下层衬底之间键合的同时，实现低缺陷单晶膜的外延生长。这使得外延膜能够随后被释放，以便与其他系统集成，并使生长衬底得以重复使用。这种方法适用于键合中有离子成分的材料体系，这使得它对III-V族合金特别有吸引力，III-V族合金是一类技术上很重要的材料。通过化学气相沉积生长石墨烯并通过聚合物手柄湿法转移到III-V族衬底上，是一种潜在可扩展且低成本的方法，可为这些材料的远程外延制备所需的生长表面，然而，水的存在会促进III-V族氧化层的形成，从而降低随后生长的外延膜的质量。这项工作展示了使用氩离子束在单层石墨烯界面层中可控地引入缺陷，从而尽管在衬底/石墨烯界面存在原生氧化物，仍能通过分子束外延生长单晶GaAs膜。研究表明了一种缺陷引发横向过生长与远程外延共同促成膜合并的混合机制。GaAs膜的剥离揭示了缺陷引发形核位点的存在，这突出表明，对于这种方法未来的大面积发展而言，需要在缺陷引入对晶体质量的益处与随后膜剥离的要求之间取得平衡。
