Resilient Growth of a Highly Crystalline Topological Insulator-Superconductor Heterostructure Enabled by an Ex Situ Nitride Film.

Highly crystalline and easily feasible topological insulator-superconductor (TI-SC) heterostructures are crucial for the development of practical topological qubit devices. The optimal superconducting layer for TI-SC heterostructures should be highly resilient against external contamination and structurally compatible with TIs. In this study, we provide a solution to this challenge by showcasing the growth of a highly crystalline TI-SC heterostructure using refractory TiN (111) as the superconducting layer. This approach can eliminate the need for in situ cleavage or growth. More importantly, the TiN surface shows high resilience against contaminations during air exposure, as demonstrated by the successful recyclable growth of Bi 2 Se 3 . Our findings indicate that TI-SC heterostructures based on nitride films are compatible with device fabrication techniques, paving the way to the realization of practical topological qubit devices in the future.