天津大学马雷和de Heer, Walt A.团队报道了碳化硅上的超高迁移率半导体外延石墨烯。相关研究成果于2024年1月3日发表于国际顶尖学术期刊《自然》。

由于石墨烯中缺乏固有带隙，半导体石墨烯在石墨烯纳米电子学中发挥着重要作用。在过去的二十年里，通过量子限制或化学功能化来改变带隙的尝试未能产生可行的半导体石墨烯。

该文中，研究人员证明了单晶碳化硅衬底上的半导体表观石墨烯（SEG）具有0.6eV的带隙和超过5000cm²V^-1s^-1的室温迁移率，是硅的10倍，是其他二维半导体的20倍。众所周知，当硅从碳化硅晶体表面蒸发时，富含碳的表面结晶以产生石墨烯多层。在SiC的硅端接面上形成的第一石墨层是部分共价结合到SiC表面的绝缘表观石墨层。光谱测量该缓冲层具有半导体信号，但由于无序，该层的迁移率受到限制。

该文中，研究人员展示了一种准平衡退火方法，该方法在宏观原子平坦的阶地上产生SEG（即有序的缓冲层）。SEG晶格与SiC衬底对准。它具有化学、机械和热稳定性，可以使用传统的半导体制造技术进行图案化并无缝连接到半金属外延烯。这些基本特性使SEG适用于纳米电子学。

附：英文原文

Title: Ultrahigh-mobility semiconducting epitaxial graphene on silicon carbide

Author: Zhao, Jian, Ji, Peixuan, Li, Yaqi, Li, Rui, Zhang, Kaimin, Tian, Hao, Yu, Kaicheng, Bian, Boyue, Hao, Luzhen, Xiao, Xue, Griffin, Will, Dudeck, Noel, Moro, Ramiro, Ma, Lei, de Heer, Walt A.

Issue&Volume: 2024-01-03

Abstract: Semiconducting graphene plays an important part in graphene nanoelectronics because of the lack of an intrinsic bandgap in graphene1. In the past two decades, attempts to modify the bandgap either by quantum confinement or by chemical functionalization failed to produce viable semiconducting graphene. Here we demonstrate that semiconducting epigraphene (SEG) on single-crystal silicon carbide substrates has a band gap of 0.6eV and room temperature mobilities exceeding 5,000cm2V1s1, which is 10 times larger than that of silicon and 20 times larger than that of the other two-dimensional semiconductors. It is well known that when silicon evaporates from silicon carbide crystal surfaces, the carbon-rich surface crystallizes to produce graphene multilayers2. The first graphitic layer to form on the silicon-terminated face of SiC is an insulating epigraphene layer that is partially covalently bonded to the SiC surface3. Spectroscopic measurements of this buffer layer4 demonstrated semiconducting signatures4, but the mobilities of this layer were limited because of disorder5. Here we demonstrate a quasi-equilibrium annealing method that produces SEG (that is, a well-ordered buffer layer) on macroscopic atomically flat terraces. The SEG lattice is aligned with the SiC substrate. It is chemically, mechanically and thermally robust and can be patterned and seamlessly connected to semimetallic epigraphene using conventional semiconductor fabrication techniques. These essential properties make SEG suitable for nanoelectronics.

DOI: 10.1038/s41586-023-06811-0

Source: https://www.nature.com/articles/s41586-023-06811-0