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Epitaxially Driven Phase Selectivity of Sn in Hybrid Quantum Nanowires

Hybrid semiconductor/superconductor nanowires constitute a pervasive platform for studying gate-tunable superconductivity and the emergence of topological behavior. Their low-dimensionality and crystal structure flexibility facilitate novel heterostructure growth and efficient material optimization; crucial prerequisites for accurately constructing complex multi-component quantum materials. Here, we present an extensive optimization of Sn growth on InSb, InAsSb and InAs nanowires. We demonstrate how the growth conditions and the crystal structure/symmetry of the semiconductor drive the formation of either semi-metallic $\mathrm{α-Sn}$ or superconducting $\mathrm{β-Sn}$. For InAs nanowires, we obtain phase-pure, superconducting $\mathrm{β-Sn}$ shells. However, for InSb and InAsSb nanowires, an initial epitaxial $\mathrm{α-Sn}$ phase evolves into a polycrystalline shell of coexisting $\mathrmα$ and $\mathrmβ$ phases, where the $β/α$ volume ratio increases with Sn shell thickness. Whether these nanowires exhibit superconductivity or not critically relies on the $\mathrm{β-Sn}$ content. Therefore, this work provides key insights into Sn phase control on a variety of semiconductors, with consequences for the yield of superconducting hybrids suitable for generating topological systems.