Ex situ annealing effect on Nb thin films prepared by DC magnetron sputtering

Abstract

We studied effect of ex situ annealing on the superconductivity of Nb thin films on a silicon wafer prepared using DC magnetron sputtering. Fifty-nanometer thick Nb thin films were deposited using a 4-in. target under an Ar pressure of 7.5 x 10(-3) Torr with a DC power of 400W and then annealed at a base pressure of 4 x 10(-6) Torr in a separate chamber. The annealing process was performed at 50, 80, 100, 150, and 300 degrees C for 15 min. The properties of the annealed Nb thin films, including the superconducting transition temperature, were investigated. The results were analyzed in association with their structural changes as observed by X-ray diffraction and scanning electron microscopy. (C) 2011 Elsevier B.V. All rights reserved.