Preparation and properties of Nb/Al-AlO/sub x//Nb multilayers

Abstract
The authors have deposited Nb/Al-AlO/sub x//Nb multilayers on Si substrates by DC and RF magnetron sputtering. To assist the fabrication of stacked tunnel junctions they investigated the layers by transmission electron microscopy and anodization spectroscopy. The accumulated internal mechanical stress in the niobium films depends on the argon sputtering pressure and was analyzed by the X-ray stress evaluation method. Up to ten junctions in one stack were prepared. Performance of the junctions is discussed on basis of I-V characteristics and Fraunhofer patterns.<>