Study of Stress and Morphology of Superconducting Niobium Thin Films

Intrinsic stress, surface morphology and crystallographic structure of superconducting thin films play an important role in determining the quality of their superconducting properties and the Josephson junctions made of them. Nb thin films deposited by DC magnetron sputtering with various deposition conditions were studied using curvature method, atomic force microscopy and X-ray diffraction. The role of sputtering pressure, gun operating parameters, substrate temperature and substrate materials on film morphology, crystallographic structure and intrinsic stress are investigated. Superconducting transition temperatures of the films were measured and relationship between the transition temperatures and deposition conditions were studied.