Niobium nitride Josephson devices with semiconductor barriers. Final report 27 May 80-25 Sep 81
Semiconductor barriers are investigated as a means of producing NbN-barrier-NbN and NbN-barrier-Nb Josephson devices. Chemical vapor deposition of silicon and germanium polycrystalline barriers onto NbN substrates and sputter deposition of amorphous silicon onto NbN substrates were used to produce the barrier layers. NbN-aSi-Nb tunnel junctions which had a Vm (product of critical current and subgap resistance) as high as 15 mV were fabricated. Phosphorus doped Ge barriers about 60 A thick produced tunnel junctions with Vm = 2-3 mV. Super Schottky diodes were produced with boron doped germanium barriers about 130 A thick. Boron doped germanium barriers about 60-70 A thick were observed to have Josephson coupling with good uniformity as judged by ideal threshold curves, but had non-ideal tunneling characteristics. NbN-Ge-NbN devices were produced by first depositing the trilayer structure over the entire wafer and then isolating the desired junctions by thermally oxidizing the upper NbN layer between devices, with the device area being protected from oxidization by a patterned SiO2 layer. Some correlation between good tunneling characteristics and the crystal structure and high optical reflectivity of the lower NbN electrode was observed.
- Research Organization:
- Sperry Research Center, Sudbury, MA (USA)
- OSTI ID:
- 5144712
- Report Number(s):
- AD-A-110128/6; SRC-CR-81-65
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
JOSEPHSON JUNCTIONS
FABRICATION
CHEMICAL VAPOR DEPOSITION
DESIGN
GERMANIUM
NIOBIUM NITRIDES
SCHOTTKY BARRIER DIODES
SILICON
SPUTTERING
CHEMICAL COATING
DEPOSITION
ELEMENTS
JUNCTIONS
METALS
NIOBIUM COMPOUNDS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SEMIMETALS
SUPERCONDUCTING JUNCTIONS
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
420201* - Engineering- Cryogenic Equipment & Devices