Response of Nb-aSi-Nb junctions to 604 GHz radiation
Abstract
The response of Nb-aSi-Nb junctions to 604 GHz radiation from an optically pumped far-infrared (FIR) laser source has been measured. These rugged and thermally cyclable junctions situated at the midpoint of 180 microns long dipole antennas, were fabricated on oxidized silicon wafers using the Selective Niobium Anodization Process (SNAP). Josephson current densities were approximately 9,000 A/sq cm, the McCumber parameters beta-c were approximately 3.5, and the Josephson plasma frequencies omega-J approximately 2.5 x 10 to the 12th. On a junction with a normal state resistance of approximately 7 ohms, three Josephson steps and one photon-assisted tunneling step were observed. The widths of the Josephson steps were studied as a function of the laser power. An RSJ model computer simulation with a nonlinear quasiparticle conductance and an RF current bias (assumed because of the low junction resistance) is able to account reasonably well for the laser-power dependence of the critical current (zeroth step) and the second step. However, the temperature dependence is more complex, and a discrepancy still exists between the RSJ model calculation and the data for the hysteretic first step.
- Publication:
-
IEEE Transactions on Magnetics
- Pub Date:
- March 1985
- DOI:
- 10.1109/TMAG.1985.1063816
- Bibcode:
- 1985ITM....21..219D
- Keywords:
-
- Infrared Detectors;
- Josephson Junctions;
- Niobium;
- Silicon Junctions;
- Superconductors;
- Volt-Ampere Characteristics;
- Amorphous Materials;
- Computerized Simulation;
- Current Density;
- Fabrication;
- Far Infrared Radiation;
- Infrared Lasers;
- Insulators;
- Spectral Sensitivity;
- Submillimeter Waves;
- Electronics and Electrical Engineering