Effect of Vacuum Annealing on Superconducting Properties of Niobium Films

Thermal annealing of sputtered Nb films has been carried out in vacuum between 200 and 600-degrees-C. Electrical properties have been seen to worsen over 200-degrees-C while grain size improve until 400-degrees-C and decrease over 600-degrees-C.Possible applications of annealing process on Nb film have been evaluated. Resistivity and grain size data have been used to calculate electron reflectivity at the grain boundaries through Mayadas-Shatzkes theory; this has indicated that conducibility degradation can be due to oxygen diffusion into the grains.