High-Quality InSb Nanowires Grown by Molecular-Beam Epitaxy via Precise Catalyst Modulation

Semiconductor InSb nanowires are a major material candidate for topological quantum computation. The nanowires in current devices were mostly grown using metal-organic chemical vapor deposition, which is incompatible with in situ growth of superconductors, a crucial requirement for low-disorder devices. Growth of InSb nanowires using molecular-beam epitaxy (MBE) can address this issue. So far, studies on MBE-grown InSb remain limited due to an extremely narrow parameter window for growth and reproducibility. Moreover, the use of foreign catalysts can introduce deep-level impurities. Here we report self-catalyzed MBE growth of InSb nanowires without those foreign catalysts. We first grow GaAs nanowire stems and then convert Ga catalyst droplets into In droplets in situ. Axial heteroepitaxial growth of InSb can be realized through the In droplets on top of GaAs stems. We further find that a low flux suppresses radial growth, enabling linear length tuning from 0.8 to 2.6 μm with growth time while the diameter stays nearly constant. These InSb nanowires have a pure zinc-blende structure free of twins and stacking faults. Transport measurements reveal an electron mobility near 19,000 cm2 V-1 s-1. Moreover, the observation of quasi-ballistic transport, quantum dots, and Kondo correlations demonstrates the coherent quantum transport capability of the MBE-grown InSb nanowires. Our work provides a substrate-independent, self-catalyzed route for the controllable synthesis of high-quality InSb nanowires, establishing a robust material platform for high-performance InSb-based electronic and quantum devices.