Homogeneous Large-Area Quasi-Free-Standing Monolayer and Bilayer Graphene on SiC
Homogeneous Large-Area Quasi-Free-Standing Monolayer and Bilayer Graphene on SiC
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DOI：
10.1021/acsanm.8b02093
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发表时间：
2019-02-01
影响因子：
5.9
通讯作者：
Schumacher, H. W.
中科院分区：
文献类型：
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作者：
Pakdehi, D. Momeni;Pierz, K.;Schumacher, H. W.
在这项研究中，我们首先证明了石墨烯外延生长过程中的氩气流量是控制缓冲层和石墨烯层质量的重要参数。原子力显微镜（AFM）和低能电子衍射（LEED）测试表明，在压力和温度保持不变的情况下，SiC衬底的分解与Ar质量流量密切相关。我们的数据是通过一个基于SiC分解速率竞争的模型来解释的，由Ar流控制，在SiC表面平衡过程下形成均匀的石墨烯缓冲层。适当选择一组生长参数可以生长出无缺陷、超光滑、相干的无石墨烯缓冲层和无双层单层石墨烯片，通过插氢可以将其转化为大面积高质量的准独立单层和双层石墨烯片。原子力显微镜、扫描隧道显微镜、拉曼光谱和电子输运测量强调了所得到的准独立层的优异均匀性。在四点探针配置下的电子输运测量揭示了在μ m和mm尺度上均匀的低电阻各向异性。
In this study, we first show that the argon flow during epitaxial graphene growth is an important parameter to control the quality of the buffer and the graphene layer. Atomic force microscopy (AFM) and low-energy electron diffraction (LEED) measurements reveal that the decomposition of the SiC substrate strongly depends on the Ar mass flow rate while pressure and temperature are kept constant. Our data are interpreted by a model based on the competition of the SiC decomposition rate, controlled by the Ar flow, with a uniform graphene buffer layer formation under the equilibrium process at the SiC surface. The proper choice of a set of growth parameters allows the growth of a defect-free, ultrasmooth, and coherent graphene-free buffer layer and bilayer-free monolayer graphene sheets which can be transformed into large-area high-quality quasi-free-standing monolayer and bilayer graphene by hydrogen intercalation. AFM, scanning tunneling microscopy, Raman spectroscopy, and electronic transport measurements underline the excellent homogeneity of the resulting quasi-free-standing layers. Electronic transport measurements in four-point probe configuration reveal a homogeneous low resistance anisotropy on both mu m and mm scales.