Abstract Tunneling barriers, in particular superconductive tunneling barriers (Josephson barriers), are prepared in a vacuum chamber maintained at a low atmospheric pressure using an oxygen glow discharge which produces stable and reproducible superconductive tunneling devices. To prepare a Pb-Pbx Oy-Pb barrier the first lead film is placed in a vacuum chamber and charged to a negative potential with regard to the positive ions by fast electrons from the plasma charge. Oxygen gas molecules bombard the first lead film where they probably disassociate into two oxygen atoms. A surface reaction takes place which produces a lead-oxide insulating layer in the first lead film. After this lead-oxide layer has reached a predetermined thickness, the plasma is extinguished and the oxygen-lead reaction stops. Immediately after the oxide formation, a second lead layer is evaporated onto the oxide layer to form a tunneling barrier of the Josephson type. Instead of forming a lead-oxide insulating layer into the first lead film, polymerized organic molecules may be formed on the lead surface by the high energy bombardment.
A process as defined by claim 1 wherein said first and second metal films are composed of lead.
Claim 2
Dependent Claim
20 words
A process as defined by claim 1 wherein said noble gas pressure is no greater than about 10 3 Torr.
Claim 3
Dependent Claim
27 words
A process as defined by claim 1 wherein said first ionizing voltage and said A.C. ionizing voltage are each in the range of 5,000 to 15,000 volts.
Claim 4
Dependent Claim
20 words
A process as defined by claim 1 wherein said oxygen pressure is in the range of about 10 3 Torr.
Claim 5
Dependent Claim
30 words
A process as defined by claim 1 including the further step of applying a negative potential to said first metal film during the application of ionizing voltage to said electrodes.
Claim 6
Dependent Claim
18 words
A process as defined by claim 1 wherein said first and second metal films are composed of tin.
Claim 7
Dependent Claim
160 words
A process for the fabrication of a superconductive tunneling device comprising the steps of: placing a first metal film in a vacuum chamber and evacuating the chamber to remove undesirable gases, backfilling the chamber to provide a very small pressure of a first inert gas, applying a first ionizing voltage to a pair of spaced electrodes in the vacuum chamber, thereby bombarding said film with ions of said inert gas to provide a clean metal surface, then replacing the inert gas with a very small pressure of a second gas, the ions of which are capable of forming an insulating film on said first metal film, applying an A.C. ionizing voltage to said electrodes to ionize said second gas and thereby bombard the clean surface with ions of said second gas for a time sufficient to form an insulating film in the range of about 10 - 15 angstroms thick, then depositing a second metal film on said insulating film.
Claim 8
Dependent Claim
13 words
A process as defined by claim 8 wherein said second gas is nitrogen.
Claim 9
Dependent Claim
16 words
A process as defined by claim 8 wherein said second gas is a polymerizable organic vapor.