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Surface Study of Nb/Cu Films for Cavity Deposition by ECR Plasma

Niobium (Nb) thin film deposited on copper (Cu) cavities through electron cyclotron resonance (ECR) plasma appears to be an attractive alternative technique for fabricating superconducting radio frequency cavities to be used in particle accelerators. The performance of these obtained Nb/Cu cavities is expected to depend on the surface characteristics of the Nb films. In this report, we investigate the influence of deposition energy on surface morphology, microstructure, and chemical composition of Nb films deposited on small Cu disks employing a metallographic optical microscope, a 3-D profilometer, a scanning electron microscope, and a dynamic secondary ion mass spectrometry. The results will be compared with those obtained on Nb surfaces treated by BCP, EP, and BEP.