Measuring and Tuning the Potential Landscape of Electrostatically Defined Quantum Dots in Graphene
Measuring and Tuning the Potential Landscape of Electrostatically Defined Quantum Dots in Graphene
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DOI：
10.1021/acs.nanolett.1c00791
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发表时间：
2021-06-07
期刊：
影响因子：
10.8
通讯作者：
Brar, Victor W.
中科院分区：
文献类型：
--
作者：
Behn, Wyatt A.;Krebs, Zachary J.;Brar, Victor W.
我们使用开尔文探针力显微镜（KPFM）探测石墨烯/六方氮化硼（hBN）异质结构中静电定义的量子点（QD）的载流子依赖电位。我们表明，门相关的测量，使校准方案，纠正在典型的KPFM测量固有的不确定性，并准确地重建潜在的井剖面。我们的测量揭示了如何随着载流子浓度的变化，我们与石墨烯的功函数对载流子密度的非线性依赖关系。这些变化移动了量子点中准束缚态的能级，我们可以通过扫描隧道光谱（STS）进行测量。我们表明，实验提取的能级密切比较从重建的KPFM数据计算的波函数。这种方法，其中KPFM和STS数据同时从二维材料中获得，允许准粒子响应的静电势以自洽的方式来确定。
We use Kelvin probe force microscopy (KPFM) to probe the carrier-dependent potential of an electrostatically defined quantum dot (QD) in a graphene/hexagonal boron nitride (hBN) heterostructure. We show that gate-dependent measurements enable a calibration scheme that corrects for uncertainty inherent in typical KPFM measurements and accurately reconstructs the potential well profile. Our measurements reveal how the well changes with carrier concentration, which we associate with the nonlinear dependence of graphene's work function on carrier density. These changes shift the energy levels of quasi-bound states in the QD which we can measure via scanning tunneling spectroscopy (STS). We show that the experimentally extracted energy levels closely compare with wave functions calculated from the reconstructed KPFM data. This methodology, where KPFM and STS data are simultaneously acquired from 2D materials, allows the quasiparticle response to an electrostatic potential to be determined in a self-consistent way.