Tuning Epitaxial Growth of Nb on MgO(100)

Abstract

Niobium thin films are central to many applications, such as superconducting radio‐frequency cavities and superconducting qubits, due to its relatively high superconducting temperature and easiness to form heterostructures. However, literature on epitaxial growth of Nb on one of the most commonly used substrates, that is MgO, reports contradicting results. In the present parametric study, a coherent picture of how the crystalline orientation and the film morphology depend on the growth parameters is presented. The effects of growth parameters such as growth temperature, growth rate, deposition technique, and surface quality on the transport properties of the superconductor are discussed. In light of the new findings, an overview on previously published results and proposed nucleation and growth mechanisms is also given.