Tailoring Kinetics on a Topological Insulator Surface by Defect-Induced Strain: Pb Mobility on Bi2Te3
Tailoring Kinetics on a Topological Insulator Surface by Defect-Induced Strain: Pb Mobility on Bi2Te3
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通过缺陷引起的应变调整拓扑绝缘体表面的动力学：Bi2Te3 上的 Pb 迁移率
DOI：
10.1021/acs.nanolett.6b01604
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发表时间：
2016
期刊：
影响因子：
10.8
通讯作者：
Han Yong
中科院分区：
文献类型：
--
作者：
Huang Wen-Kai;Zhang Kai-Wen;Yang Chao-Long;Ding Haifeng;Wan Xiangang;Li Shao-Chun;Evans James W.;Han Yong
基于bi2te3型拓扑绝缘体（TIs）的异质外延结构表现出奇异的量子现象。为了对这些现象进行最优表征，需要在这种ti上的薄膜生长过程中控制界面结构。在这个过程中，原子迁移是一个关键因素。我们证明了在Si(111)-7 × 7衬底上生长的Bi2Te3（111）薄膜中固有的点状缺陷周围产生的工程局部应变ε可以改变Pb在Bi2Te3（111）表面的迁移率。扫描隧道显微镜对Pb吸附原子和簇分布的观察和第一性原理密度泛函理论（DFT）对Pb吸附原子在Bi2Te3（111）表面的吸附能和扩散势垒的分析表明，ε对Pb吸附原子在Bi2Te3（111）表面的吸附能和扩散势垒有显著影响。令人惊讶的是，由于在临界拉伸应变εc≈0.8%处稳定吸附位点的分叉，edc显示出对ε的尖状依赖。这与以往所有关注传统金属或半导体表面的研究形成了非常不同的应变依赖扩散率。结合DFT结果的Pb沉积、扩散和不可逆聚集的动力学蒙特卡罗模拟显示，附着原子和簇的分布与我们的实验观察相一致。
Heteroepitaxial structures based on Bi2Te3-type topological insulators (TIs) exhibit exotic quantum phenomena. For optimal characterization of these phenomena, it is desirable to control the interface structure during film growth on such TIs. In this process, adatom mobility is a key factor. We demonstrate that Pb mobility on the Bi2Te3(111) surface can be modified by the engineering local strain, ε, which is induced around the point-like defects intrinsically forming in the Bi2Te3(111) thin film grown on a Si(111)-7 × 7 substrate. Scanning tunneling microscopy observations of Pb adatom and cluster distributions and first-principles density functional theory (DFT) analyses of the adsorption energy and diffusion barrierEdof Pb adatom on Bi2Te3(111) surface show a significant influence of ε. Surprisingly,Edreveals a cusp-like dependence on ε due to a bifurcation in the position of the stable adsorption site at the critical tensile strain εc≈ 0.8%. This constitutes a very different strain-dependence of diffusivity from all previous studies focusing on conventional metal or semiconductor surfaces. Kinetic Monte Carlo simulations of Pb deposition, diffusion, and irreversible aggregation incorporating the DFT results reveal adatom and cluster distributions compatible with our experimental observations.