Hatta Shinichiro, Obayashi Ko, Okuyama Hiroshi, Aruga Tetsuya
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan.
Sci Rep. 2021 Mar 11;11(1):5742. doi: 10.1038/s41598-021-85078-9.
While the van der Waals (vdW) interface in layered materials hinders the transport of charge carriers in the vertical direction, it serves a good horizontal conduction path. We have investigated electrical conduction of few quintuple-layer (QL) [Formula: see text] films by in situ four-point probe conductivity measurement. The impact of the vdW (Te-Te) interface appeared as a large conductivity increase with increasing thickness from 1 to 2 QL. Angle-resolved photoelectron spectroscopy and first-principles calculations reveal the confinement of bulk-like conduction band (CB) state into the vdW interface. Our analysis based on the Boltzmann equation showed that the conduction of the CB has a long mean free path compared to the surface-state conduction. This is mainly attributed to the spatial separation of the CB electrons and the donor defects located at the Bi sites.
虽然层状材料中的范德华（vdW）界面阻碍了载流子在垂直方向上的传输，但它提供了良好的水平传导路径。我们通过原位四点探针电导率测量研究了少数五层（QL）[化学式：见原文]薄膜的电导率。随着厚度从1 QL增加到2 QL，vdW（Te-Te）界面的影响表现为电导率大幅增加。角分辨光电子能谱和第一性原理计算揭示了类体导带（CB）态被限制在vdW界面中。我们基于玻尔兹曼方程的分析表明，与表面态传导相比，CB的传导具有较长的平均自由程。这主要归因于CB电子与位于Bi位点的施主缺陷的空间分离。
