METHOD TO CONTROL MICROSTRUCTURE OF EVAPORATED Nb FILMS FOR JOSEPHSON JUNCTIONS
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
Controlling sputter preclean voltage and duration causes a substrate surface to provide controlled microstructure niobium base electrode films for use in Josephson devices. In mechanically stable Josephson junctions, obtained using niobium films as the base electrode and lead-indium-gold films as the counterelectrode material, it is essential to control the niobium film microstructure without adding any impurities. Degrees of (110) fiber structure of niobium films, which are deposited onto sputter-cleaned oxidized silicon wafers, are measured by an X-ray diffraction technique, with the results shown in the figure, as a function of sputtering voltage used for precleaning the substrates. The film microstructure is very sensitive to the sputtering voltage used.