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Heterostructures of tellurium on NbSe2 from sub-monolayer to few-layer films.
Nanoscale ( IF 5.8 ) Pub Date : 2020-01-08 , DOI: 10.1039/c9nr09445h
Jing-Jing Xian 1 , Cong Wang , Zhi-Mo Zhang , Le Qin , Wei Ji , Fang-Chu Chen , Xuan Luo , Yu-Ping Sun , Wen-Hao Zhang , Ying-Shuang Fu
Affiliation  

As a single-elemental system, tellurium can exist stably in the form of layers with an intriguing multivalence character, which constructs a new member of the 2D family. However, the growth and electronic structure of tellurium films are still far from known at present. Here, combined with molecular beam epitaxy, scanning tunneling microscopy/spectroscopy measurements and density functional theory calculations, we report the geometric and electronic structures of tellurium grown on NbSe2 from sub-monolayer to few-layer films. At the sub-monolayer coverage, we obtain two types of adatom-induced ordered superstructures that are strongly coupled with NbSe2. With the increase in coverage, the few-layer tellurium films adopt the α-phase form, showing internal strain-induced ripple patterns in the few-layers and bulk-like in thick layers with distinct edge geometries. The band gap of α-tellurium films decreases with the increase in thickness, which is associated with notable in-gap states. These observations, corroborated with DFT calculations, emphasize the important role of the NbSe2 substrate in modulating the structural and electronic properties of tellurium films. Moreover, the interaction between tellurium adatoms and tellurium films leads to √2 × √2 surface reconstruction prior to a new monolayer, conforming to our theoretical calculations. Our work clarifies the kinetic growth of tellurium films on NbSe2 and reveals the tunability of electronic properties via substrate modulation or surface decoration.

中文翻译:

NbSe2上碲的亚结构从亚单层薄膜到几层薄膜。

作为单元素系统,碲可以稳定地以具有吸引人的多价特征的层的形式存在,从而构成了2D族的新成员。然而,碲薄膜的生长和电子结构目前仍是未知的。在这里,结合分子束外延,扫描隧道显微镜/光谱学测量和密度泛函理论计算,我们报告了NbSe2上生长的碲的几何结构和电子结构,其结构从亚单层到几层。在亚单层覆盖范围内,我们获得了两种类型的与NbSe2强烈耦合的吸附原子诱导的有序超结构。随着覆盖率的增加,几层碲膜采用α相形式,在几层中显示出内部应变引起的波纹图案,在厚层中具有类似体边缘几何形状的块状样。α-碲膜的带隙随着厚度的增加而减小,这与显着的间隙内状态有关。这些观察结果得到DFT计算的证实,强调了NbSe2基质在调节碲薄膜的结构和电子性能中的重要作用。而且,碲原子与碲膜之间的相互作用导致在形成新的单层之前√2×√2表面重建,这符合我们的理论计算。我们的工作阐明了NbSe2上碲薄膜的动力学生长,并揭示了通过基材调制或表面装饰实现的电子性能的可调性。α-碲膜的带隙随着厚度的增加而减小,这与显着的间隙内状态有关。这些观察结果得到DFT计算的证实,强调了NbSe2基质在调节碲薄膜的结构和电子性能中的重要作用。而且,碲原子与碲膜之间的相互作用导致在形成新的单层之前√2×√2表面重建,这符合我们的理论计算。我们的工作阐明了NbSe2上碲薄膜的动力学生长,并揭示了通过基材调制或表面装饰实现的电子性能的可调性。α-碲膜的带隙随着厚度的增加而减小,这与显着的间隙内状态有关。这些观察结果得到DFT计算的证实,强调了NbSe2基质在调节碲薄膜的结构和电子性能中的重要作用。此外,碲原子与碲膜之间的相互作用导致在形成新的单层之前√2×√2表面重建,这符合我们的理论计算。我们的工作阐明了NbSe2上碲薄膜的动力学生长,并揭示了通过基材调制或表面装饰实现的电子性能的可调性。强调了NbSe2衬底在调节碲薄膜的结构和电子性能中的重要作用。而且,碲原子与碲膜之间的相互作用导致在形成新的单层之前√2×√2表面重建,这符合我们的理论计算。我们的工作阐明了NbSe2上碲薄膜的动力学生长,并揭示了通过基材调制或表面装饰实现的电子性能的可调性。强调了NbSe2衬底在调节碲薄膜的结构和电子性能中的重要作用。而且,碲原子与碲膜之间的相互作用导致在形成新的单层之前√2×√2表面重建,这符合我们的理论计算。我们的工作阐明了NbSe2上碲薄膜的动力学生长,并揭示了通过基材调制或表面装饰实现的电子性能的可调性。
更新日期:2020-01-08
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