Fabrication of Nb-NbO/sub x/-Pb Josephson tunnel junctions using rf glow-discharge oxidation

Journal Article · Wed Oct 31 23:00:00 EST 1979 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.325865· OSTI ID:5853754

Karulkar, P C; Nordman, J E

An rf glow-discharge oxidation technique has been applied to the fabrication of Nb-NbO/sub x/-Pb Josephson tunnel junctions which exhibit quasiparticle current densities up to 10/sup 4/ A/cm/sup 2/ at the sum of the gaps (i.e., junction resistances as low as 10/sup -7/ ..cap omega.. cm/sup 2/). The dependence of the impedance level and the shape of the junction V-I curve on the oxidation parameters (e.g., oxidation time, rf bias voltage, the composition, and the pressure of the argon-oxygen mixture) have been investigated. Good junctions were obtained by using very low rf peak-to-peak voltage (approx. =60 V) and an oxidation period of 10 min or less. The junction resistance can be controlled by varying the partial pressure of oxygen (less than 3 x 10/sup -4/ Torr) while using a partial pressure of argon high enough (approx. =10/sup -2/ Torr) to sustain a steady rf glow discharge. The results also indicate that sputter removal of niobium oxide is virtually absent in this rf glow-discharge oxidation process. The dependence of the junction resistance on the glow-discharge parameters is qualitatively explained by considering the effects of the parameters on the concentration of the oxidizing species in the vicinity of the substrate.

• Research Organization: University of Wisconsin, Madison, Wisconsin 53706
• OSTI ID: 5853754
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 50:11; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ARGON
CHALCOGENIDES
CHEMICAL REACTIONS
CRYOGENIC FLUIDS
CURRENT DENSITY
DATA
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRIC DISCHARGES
ELECTRICAL PROPERTIES
ELEMENTS
FABRICATION
FLUIDS
INFORMATION
JOSEPHSON JUNCTIONS
LEAD
METALS
MIXTURES
NIOBIUM
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
NONMETALS
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRESSURE DEPENDENCE
QUANTITY RATIO
RARE GASES
REFRACTORY METALS
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SUPERCONDUCTING JUNCTIONS
TIME DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNNEL DIODES