Reducing disorder in PbTe nanowires for Majorana research

Topological superconductivity can arise in semiconductor nanowires with strong spin-orbit coupling when brought in proximity with an s-wave superconductor. A remarkable manifestation of topological superconductivity is the prediction of Majorana zero modes at the ends of these nanowires, following non-Abelian statistics and serving as a foundation for topological quantum computing. The realization of topological qubits and braiding operations requires scalable and disorder-free nanowire networks. Although the scalability of in-plane InAs and InSb nanowires, combined with the shadow-wall growth of superconductors, has been demonstrated, the discernible lattice mismatch at the nanowire-substrate interface introduces disorder, posing a significant hurdle to progress. In this work, we address this challenge by combining selective area and shadow-wall growth to fabricate PbTe-Pb hybrid nanowires—a promising Majorana system—on a nearly perfectly lattice-matched ‘substrate’, Pb_1-xEu_xTe. Transmission electron microscopy reveals an atomically sharp surface of the Pb_1-xEu_xTe and clean interface between the PbTe nanowire and the Pb overlayer. The nearly ideal interface condition, coupled with the effective charge impurity screening arising from the large dielectric constant of PbTe, shows potential for creating a clean nanowire system to explore Majorana zero modes and advance topological quantum computing.