Electronic structure and epitaxy of InSb-CdTe core-shell nanowires

Indium antimonide (InSb) nanowires are considered prime candidates for the emergent semiconducting-superconducting hybrids used for the topological Majorana particles research. A common concern in current nanowire devices is the overly strong superconducting-semiconducting coupling, which tends to overwhelm the intrinsic properties of the semiconducting nanowire. It has been proposed that adding a tunnel barrier at the nanowire-superconductor interface modulates this coupling.

Here, we add cadmium telluride (CdTe) shells around the InSb nanowires and investigate their suitability to serve as a tunnel barrier between a superconductor and InSb nanowires based on the electronic structure of the InSb-CdTe interface, the growth, and epitaxy of the CdTe on InSb. We use density functional theory to extract the individual bandgaps of InSb and CdTe as well as the band alignment at the interface. Moreover, we demonstrate that these insulating, lattice matched CdTe shells can be grown epitaxially on the InSb nanowires without interfacial strain or defects. The obtained defect-free and epitaxial interfaces along with the control over shell thickness we achieve indicate the potential of these CdTe shells to act as a control knob that tunes the superconducting-semiconducting coupling.