Abstract: A Josephson tunnel junction device having niobium nitride superconductive electrodes includes a polycrystalline semiconductor tunneling barrier therebetween comprised of silicon, germanium, or an alloy thereof preferably deposited on the lower superconductive electrodes by vapor deposition. The barrier thickness of the junction is controlled by precision doping of the semiconductor material. The active junction is defined after the interfaces between the barrier material and the two superconductor lines are formed, retaining those active interfaces in fully unpolluted character.

Abstract: A method of fabricating lines of submicron width, comprising the steps of:providing a substrate,depositing a first layer of metal upon the substrate;spinning a photoresist layer on the metal;patterning the photoresist layer;etching the metal to undercut the photoresist edge, e.g. with a mixture for approximately ten minutes at room temperature;depositing a second layer of metal at an angle .theta..sub.1 to the photoresist edge, thereby defining a long, submicron-wide opening to the underlying substrate;depositing a chosen material, for example, metallic or semiconductor, for the bridge onto the substrate at an angle of .theta..sub.2 through the submicron-wide opening; andremoving undesired material surrounding the bridge by dissolving the photoresist in hot acetone followed by stripping the remaining two layers of metal with etchant.

Abstract: During the process of vacuum deposition, metals and materials are evaporated at a point source so as to create a vapor which is dispersed isotropically. Layers of the evaporating material are deposited as built-up layers which have sharp vertical edges or steps at the areas defined by the photoresist stencil. When the line of sight of the depositing material is from an oblique angle, the layer being deposited can have a negative slope which appears as an undercut edge. The present invention employs a lift-off overhang photoresist stencil in conjunction with a relatively high pressure of inert gas in the vacuum chamber so as to promote collision of the evaporated atoms and molecules with the inert gas.