Autonomous growth of NbN nanostructures on atomically flat AlN surfaces

Integrating the functions of superconductors and semiconductors by epitaxial growth can lead to the fabrication of quantum devices such as on-chip quantum communication systems with single-photon emitters and detectors. Furthermore, a combination of nitride superconductors and nitride semiconductors is one of the most suitable candidates for application in these quantum devices. However, the structure of superconducting NbN films grown on nitride semiconductors needs to be elucidated. In this study, we report the self-organization of NbN nanostructures that were epitaxially grown on an atomically flat AlN surface. Structural investigation of the NbN/AlN heterostructure revealed that the growth of NbN twins on the AlN surface leads to the autonomous formation of nanostructures. These results significantly contribute to the materials science of cubic transition metal nitride heteroepitaxy.