We have studied Bi2Se3 at its 2D-limit using scanning tunneling spectroscopy (STS). Bulk Bi2Se3 is a well-known topological insulator having gapless surface states. In the 2D limit, the interior of the material exhibits a band gap, whereas the periphery shows a gapless metallic state having a Dirac point. We demonstrate a method to tune the Fermi energy and hence the Dirac point of Bi2Se3 nanoplates through doping at the anionic site. For this purpose, STS measurements were carried out on the Bi2Se3 system. We have used bromide as a dopant, which turns the material to n-type in nature. As a result, STS studies infer that the Fermi energy (EF) shifted toward the conduction band and consequently the Dirac point could be found to move away from Fermi energy. Through STS measurements, we have demonstrated a correlation between the shift of Dirac point position and the dopant content. The size, shape, and compositions of Bi2Se3 nanoflakes and concentration of bromine in the doped nanostructures were determined using transmission electron microscopy, associated energy dispersive X-ray spectroscopy analysis, and X-ray diffraction.

中文翻译：

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二维拓扑绝缘体的狄拉克态：异价掺杂剂含量的影响

我们研究了毕2硒3使用扫描隧道光谱（STS）在其二维极限。散装比2硒3是众所周知的具有无间隙表面态的拓扑绝缘体。在二维极限中，材料的内部呈现出带隙，而外围呈现出具有狄拉克点的无间隙金属态。我们展示了一种调整费米能量的方法，从而调整 Bi 的狄拉克点2硒3通过在阴离子位点掺杂纳米板。为此，在 Bi 上进行了 STS 测量。2硒3系统。我们使用溴化物作为掺杂剂，它使材料本质上变成了 n 型。因此，STS 研究推断费米能量 (乙F）向导带移动，因此可以发现狄拉克点远离费米能量。通过 STS 测量，我们已经证明了狄拉克点位置的偏移与掺杂剂含量之间的相关性。Bi的大小、形状和成分2硒3使用透射电子显微镜、相关的能量色散 X 射线光谱分析和 X 射线衍射测定掺杂纳米结构中的纳米薄片和溴浓度。