Evidences of inner Se ordering in topological insulator PbBi2Te4-PbBi2Se4-PbSb2Se4 solid solutions
Evidences of inner Se ordering in topological insulator PbBi2Te4-PbBi2Se4-PbSb2Se4 solid solutions
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DOI：
10.1038/s41598-020-64742-6
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发表时间：
2020-05
影响因子：
4.6
通讯作者：
Y. Hattori;Y. Tokumoto;K. Kimoto;K. Edagawa
中科院分区：
文献类型：
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作者：
Y. Hattori;Y. Tokumoto;K. Kimoto;K. Edagawa
在拓扑绝缘体（TI）中，源自非化学计量缺陷的载流子妨碍体绝缘。然而，在（Bi，Sb）2（Te，Se）3 TI（BSTS TI）中，Se原子强烈偏好晶体结构中的特定原子位置（Se有序化），并且该有序化结构抑制点缺陷的形成并有助于体绝缘。它促进了对TI表面电子性质的理解和器件应用。在这项研究中，我们选择了Pb（Bi，Sb）2（Te，Se）4（Pb-BSTS）TI，据报道，它具有较大的带隙相比，对应的化合物BSTS TI。Se有序的几何形状进行了研究，结合国家的最先进的扫描透射电子显微镜和粉末X射线衍射。我们证明了在PbBi_2（Te，Se）_4和Pb-BSTS TI中存在内部Se有序.定量分析Se的顺序和原子的非化学计量比，如点缺陷的定性观点也被提出。Pb-BSTS TI的Se有序结构和它们的大间隙性质具有实现比常规BSTS TI更大的体绝缘的巨大潜力。
In topological insulators (TIs), carriers originating from non-stoichiometric defects hamper bulk insulation. In (Bi,Sb)2(Te,Se)3TIs (BSTS TIs), however, Se atoms strongly prefer specific atomic sites in the crystal structure (Se ordering), and this ordering structure suppresses the formation of point defects and contributes to bulk insulation. It has accelerated the understanding of TIs’ surface electron properties and device application. In this study, we select Pb(Bi,Sb)2(Te,Se)4(Pb-BSTS) TIs, which are reported to have larger bandgap compared to counterpart compound BSTS TIs. The Se ordering geometry was investigated by combining state-of-the-art scanning transmission electron microscopy and powder X-ray diffractometry. We demonstrated the existence of inner Se ordering in PbBi2(Te,Se)4and also in Pb-BSTS TIs. Quantitative analysis of Se ordering and a qualitative view of atomic non-stoichiometry such as point defects are also presented. Pb-BSTS TIs’ Se ordering structure and their large gap nature has the great potential to achieve more bulk insulation than conventional BSTS TIs.