Ultra-High Frequency Superconductive Devices
Abstract
The objective of this research program was to develop advanced superconducting tunnel junctions for application in superconducting local oscillators and superconducting mixers operating in the Terahertz (0.2 - 2.0 THz) frequency regime. The research was focused on the development of stable, all refractory, high-critical-current-density, small-area tunnel junctions based on NbN superconducting thin films. A successful process for fabrication of approx. 1 sq. micron NbN-MgO-NbN Josephson tunnel junctions was developed with the junctions having critical current densities equal to or greater than 10.000 A/sq. cm. Such junctions were found to be very rugged and reliable. In experiments in which such junctions were coupled capacitively to a nearby, on- chip, Josephson junction detector, the NbN junctions were found to be effective voltage-tunable oscillators from 300 GHz to above 1.4 Thz. Direct measurement of the response of the detector junction indicated that the oscillator voltage was typically 1.5 mV in amplitude. This indicated that the Terahertz oscillator power was of the order of 0.5 uW, of which, due to impedance mismatch, 0.01 micro W was typically coupled into the detector junction. This power is quite adequate for local oscillator applications in Terahertz mixer applications that might employ a superconducting SIS detector.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1991
- Accession Number
- ADA236795
Entities
People
- Robert A. Buhrman
Organizations
- Cornell University School of Applied and Engineering Physics