Dynamic band structure and capacitance effects in scanning tunneling spectroscopy of bilayer graphene
Dynamic band structure and capacitance effects in scanning tunneling spectroscopy of bilayer graphene
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DOI：
10.1063/1.5127078
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发表时间：
2019-09
影响因子：
4
通讯作者：
Gregory R. Holdman;Zach Krebs;Wyatt A. Behn;Keenan Smith;Kenji Watanabe;T. Taniguchi;V. Brar
中科院分区：
文献类型：
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作者：
Gregory R. Holdman;Zach Krebs;Wyatt A. Behn;Keenan Smith;Kenji Watanabe;T. Taniguchi;V. Brar
我们开发了一个完全自洽的模型来描述伯纳尔堆叠双层石墨烯（BLG）的扫描隧道光谱（STS）测量，并将我们的模型结果与实验测量结果进行比较。我们的结果表明，STS 尖端充当顶栅，改变 BLG 能带结构和费米能级，同时探测电压依赖性隧道态密度 (TDOS)。这些效应导致 TDOS 和局域态密度 (LDOS) 之间存在差异；特别是，我们表明 BLG 的带隙在 STS 测量中似乎比预期的要大，TDOS 中出现了一个附加特征，这是 STS 测量的伪影，并且通过 STS 可以观察到各个石墨烯层之间的不对称电荷分布效应。
We develop a fully self-consistent model to describe scanning tunneling spectroscopy (STS) measurements of Bernal-stacked bilayer graphene (BLG), and we compare the results of our model to experimental measurements. Our results show that the STS tip acts as a top gate that changes the BLG bandstructure and Fermi level, while simultaneously probing the voltage-dependent tunneling density of states (TDOS). These effects lead to differences between the TDOS and the local density of states (LDOS); in particular, we show that the bandgap of the BLG appears larger than expected in STS measurements, that an additional feature appears in the TDOS that is an artifact of the STS measurement, and that asymmetric charge distribution effects between the individual graphene layers are observable via STS.