Alignment of semiconducting graphene nanoribbons on vicinal Ge(001)
Alignment of semiconducting graphene nanoribbons on vicinal Ge(001)
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DOI：
10.1039/c9nr00713j
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发表时间：
2019-03-21
期刊：
影响因子：
6.7
通讯作者：
Arnold, Michael S.
中科院分区：
文献类型：
--
作者：
Jacobberger, Robert M.;Murray, Ellen A.;Arnold, Michael S.
CH 4在Ge（001）上的化学气相沉积可以实现窄的半导体石墨烯纳米带的各向异性生长，其具有主要光滑的扶手椅边缘和高性能的电荷传输特性。然而，这种纳米带不是在一个方向上对齐，而是垂直生长，这对于集成到高性能电子器件中不是最佳的。在这里，它被证明，邻位Ge（001）衬底可以用于合成扶手椅型纳米带，其中类似于90%的垂直于1.5度内垂直于错位对齐。当生长速率缓慢时，石墨烯晶体演化为纳米带。然而，随着生长速率的增加，上坡和下坡晶体边缘演变不对称。这种不对称性与下坡边缘和Ge表面之间的较强结合是一致的，例如由于密度泛函理论计算所示的不同边缘终止。通过调整生长速率和时间，实现了具有亚10 nm宽度的纳米带，其表现出优异的电荷传输特性，包括同时具有8.0 μ S的高导通态电导和场效应晶体管中570的高开/关电导比。大面积对齐的半导体带具有良好的电荷传输性能是一个重要的一步，了解各向异性纳米晶生长和集成这些材料到可扩展的，未来的半导体技术。
Chemical vapor deposition of CH4 on Ge(001) can enable anisotropic growth of narrow, semiconducting graphene nanoribbons with predominately smooth armchair edges and high-performance charge transport properties. However, such nanoribbons are not aligned in one direction but instead grow perpendicularly, which is not optimal for integration into high-performance electronics. Here, it is demonstrated that vicinal Ge(001) substrates can be used to synthesize armchair nanoribbons, of which similar to 90% are aligned within perpendicular to 1.5 degrees perpendicular to the miscut. When the growth rate is slow, graphene crystals evolve as nanoribbons. However, as the growth rate increases, the uphill and downhill crystal edges evolve asymmetrically. This asymmetry is consistent with stronger binding between the downhill edge and the Ge surface, for example due to different edge termination as shown by density functional theory calculations. By tailoring growth rate and time, nanoribbons with sub-10 nm widths that exhibit excellent charge transport characteristics, including simultaneous high on-state conductance of 8.0 mu S and a high on/off conductance ratio of 570 in field-effect transistors, are achieved. Large-area alignment of semiconducting ribbons with promising charge transport properties is an important step towards understanding the anisotropic nanoribbon growth and integrating these materials into scalable, future semiconductor technologies.