Transforming Common III-V and II-VI Semiconductor Compounds into Topological Heterostructures: The Case of CdTe/InSb Superlattices

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• 作者：Qihang Liu ; Xiuwen Zhang ; L. B. Abdalla and Alex Zunger
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：May 17, 2016
• 年：2016
• 卷：26
• 期：19
• 页码：3259-3267
• 全文大小：1386K
• ISSN：1616-3028

文摘

Currently, known topological insulators (TIs) are limited to narrow gap compounds incorporating heavy elements, thus severely limiting the material pool available for such applications. It is shown via first-principle calculations that a heterovalent superlattice made of common semiconductor building blocks can transform its non-TI components into a topological nanostructure, illustrated by III–V/II–VI superlattice InSb/CdTe. The heterovalent nature of such interfaces sets up, in the absence of interfacial atomic exchange, a natural internal electric field that along with the quantum confinement leads to band inversion, transforming these semiconductors into a topological phase while also forming a giant Rashba spin splitting. The relationship between the interfacial stability and the topological transition is revealed, finding a “window of opportunity” where both conditions can be optimized. Once a critical InSb layer thickness above ≈1.5 nm is reached, both [111] and [100] superlattices have a relative energy of 1.7–9.5 meV Å^–2, higher than that of the atomically exchanged interface and an excitation gap up to ≈150 meV, affording room-temperature quantum spin Hall effect in semiconductor superlattices. The understanding gained from this study could broaden the current, rather restricted repertoire of functionalities available from individual compounds by creating next-generation superstructured functional materials.