Hypotaxy of wafer-scale single-crystal transition metal dichalcogenides
['Moon, Donghoon', 'Jang, Hyejin', 'Lee, Gwan-Hyoung']; Nature; 2025年2月3日
『Abstract』Two-dimensional (2D) semiconductors, particularly transition metal dichalcogenides (TMDs), are promising for advanced electronics beyond silicon . Traditionally, TMDs are epitaxially grown on crystalline substrates by chemical vapour deposition. However, this approach requires post-growth transfer to target substrates, which makes controlling thickness and scalability difficult. Here we introduce a method called hypotaxy (‘hypo’ meaning downward and ‘taxy’ meaning arrangement), which enables wafer-scale single-crystal TMD growth directly on various substrates, including amorphous and lattice-mismatched substrates, while preserving crystalline alignment with an overlying 2D template. By sulfurizing or selenizing a pre-deposited metal film under graphene, aligned TMD nuclei form, coalescing into a single-crystal film as graphene is removed. This method achieves precise MoS 2 thickness control from monolayer to hundreds of layers on diverse substrates, producing 4-inch single-crystal MoS 2 with high thermal conductivity (about 120 W m K ) and mobility (around 87 cm V s ). Furthermore, nanopores created in graphene using oxygen plasma treatment allow MoS 2 growth at a lower temperature of 400 °C, compatible with back-end-of-line processes. This hypotaxy approach extends to other TMDs, such as MoSe 2 , WS 2 and WSe 2 , offering a solution to substrate limitations in conventional epitaxy and enabling wafer-scale TMDs for monolithic three-dimensional integration.
『摘要』
二维(2D)半导体,尤其是过渡金属二硫化物(TMD),有望在硅基之外的高级电子产品中大放异彩。传统上,过渡金属二硫化物是通过化学气相沉积法在晶体基底上外延生长的。然而,这种方法需要在生长后将材料转移到目标基底上,导致难以控制厚度和实现大规模生产。本文介绍了一种名为“低位排列”(“hypo”意为向下,“taxy”意为排列)的方法,该方法能够在各种基底(包括非晶基底和晶格失配基底)上直接生长晶片级的单晶过渡金属二硫化物,同时保持与上层二维模板的晶体排列一致。通过在石墨烯下对预沉积的金属膜进行硫化或硒化处理,形成排列整齐的过渡金属二硫化物晶核,随着石墨烯的去除,这些晶核合并成单晶薄膜。这种方法能够在不同基底上实现单层至数百层精确厚度的二硫化钼(MoS2)控制,制备出4英寸的单晶二硫化钼,具有高导热性(约120 W·m·K-1)和迁移率(约87 cm2·V-1·s-1)。此外,通过氧等离子体处理在石墨烯中形成的纳米孔,使得二硫化钼能够在400°C的较低温度下生长,与后端工艺兼容。这种低位排列方法还可扩展到其他过渡金属二硫化物,如二硒化钼(MoSe2)、二硫化钨(WS2)和二硒化钨(WSe2),为解决传统外延生长中的基底限制问题提供了解决方案,并使晶片级的过渡金属二硫化物能够实现单片三维集成。
『总结』
本研究提出的低位排列方法能在多种基底上直接生长晶片级单晶过渡金属二硫化物,解决了传统方法的厚度控制和大规模生产难题,为二维半导体材料的发展提供了新思路。
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