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arXiv 2104.10620cond-mat.mes-hallcond-mat.mtrl-sci
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石墨中本征缺陷的直接可视化及其对Bernal双层石墨烯电子性质的影响

Direct Visualization of Native Defects in Graphite and Their Effect on the Electronic Properties of Bernal-Stacked Bilayer Graphene

Frederic Joucken, Cristina Bena, Zhehao Ge, Ebert A. Quezada-Lopez, Sarah Pinon, Vardan Kaladzhyan, Takashi Taniguchi, Kenji Watanabe, Aires Ferreira, Jairo Velasco

摘要:

用于制备石墨烯基异质结构的石墨晶体通常被认为是无缺陷的。我们在这里报告扫描隧道显微镜的结果表明,石墨通常用于制备石墨烯器件可以包含大量的原生缺陷。表面的广泛扫描使我们能够确定原生缺陷的浓度为6.6 $\times$ 10 $^8$ cm $^{-2}$。我们进一步研究了这些本征缺陷对Bernal堆叠双层石墨烯电子性质的影响。我们观察到了门相关的谷内散射,并成功地将我们的实验结果与基于T矩阵的计算进行了比较,揭示了散射矢量分布中明显的载流子密度依赖性。我们还提出了一种用于评估短尺度散射的空间分布的技术。基于玻尔兹曼输运方程的理论分析预测,这里确定的稀释原生缺陷是一个重要的外部散射源,最终在低温下设置的迁移率。

英文摘要:

Graphite crystals used to prepare graphene-based heterostructures are generally assumed to be defect free. We report here scanning tunneling microscopy results that show graphite commonly used to prepare graphene devices can contain a significant amount of native defects. Extensive scanning of the surface allows us to determine the concentration of native defects to be 6.6$\times$10$^8$ cm$^{-2}$. We further study the effects of these native defects on the electronic properties of Bernal-stacked bilayer graphene. We observe gate-dependent intravalley scattering and successfully compare our experimental results to T-matrix-based calculations, revealing a clear carrier density dependence in the distribution of the scattering vectors. We also present a technique for evaluating the spatial distribution of short-scale scattering. A theoretical analysis based on the Boltzmann transport equation predicts that the dilute native defects identified here are an important extrinsic source of scattering, ultimately setting the mobility at low temperatures.

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