Niobium thin-film Josephson junctions using a semiconductor barrier
Thin-film superconductive tunnel junctions were fabricated using rf- sputtered germanium or indium antimonide films as barrier layers on photoetched rf-sputtered niobium patterns with evaporated lead counter electrodes. Tunneling characteristics similar in quality and shape to those of niobium-oxide-lead junctions were obtained, large Josephson currents occurring in the higher- conductanee devices. Stability of the characteristics with time was also found to be comparable to oxide junctions. Reducing the thickness of the semiconductor film appears to produce an increase in the effective tunneling barrier energy, and a model is proposed to explain this. This behavior is of importance when considering the relative merits of semiconductor barriers compared to oxide barriers for Josephson junctions. The superconductlng transition temperature of the system the theory of Keller and Fulde IJ. Low Temp. Phys.; 4: 289 (1971)) the energy splitting between the ground state and the first exclted state of Tb 3+ is found to be 5 plus or minus 1 K. The upper critical field HcT(T) of these alloys has been determined and the results have been compared with those found for La1-xGdxAl2. In this way the influe nce of the crystal field splitting of Tb3+ on the critical field data is clearly demonstrated.
- Research Organization:
- Department of Electrical Engineering, The University of Wisconsin, Madison, Wisconsin 53706
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-29-022791
- OSTI ID:
- 4315152
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 44; ISSN JAPIAU; ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Niobium nitride Josephson tunnel junctions with oxidized amorphous silicon barriers
RF-sputter-deposited magnesium oxide films as high-quality adjustable tunnel barriers