Transforming common III-V and II-VI semiconductor compounds into topological heterostructures: The case of CdTe/InSb superlattices

TL;DR

This study demonstrates how common semiconductor superlattices like InSb/CdTe can be transformed into topological phases with potential room-temperature applications through interface engineering and quantum confinement effects.

Contribution

It introduces a novel method to induce topological properties in standard semiconductor heterostructures using first-principle calculations, expanding the material options for topological insulators.

Findings

Band inversion occurs due to internal electric fields and quantum confinement.

A critical InSb layer thickness (~1.5 nm) enables topological phase transition.

Room-temperature quantum spin Hall effect is achievable in these superlattices.

Abstract

Currently known topological insulators (TIs) are limited to narrow gap compounds incorporating heavy elements, thus severely limiting the material pool available for such applications. We show via first-principle calculations how 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. We reveal the relationship between the interfacial stability and the topological transition, 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 5-14 meV/A2 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 significantly broaden the current, rather restricted repertoire of functionalities available from individual compounds by creating next-generation super-structured functional materials.