FABRICATION OF HIGH-QUALITY SUPERCONDUCTOR-INSULATOR-SUPERCONDUCTOR JUNCTIONS ON THIN SIN MEMBRANES

We have successfully fabricated high-quality and high-current density (J(c)almost-equal-to 4000 A/cm2) superconductor-insulator-superconduct or (SIS) junctions on freestanding thin (approximately 1 mum) silicon nitride (SiN) membranes. These devices can be used in a novel millimet er-wave and THz receiver system which is made using micromachining. Th e SIS junctions with planar antennas were fabricated first on a silico n wafer covered with a SiN membrane, the Si wafer underneath was then etched away using an anisotropic KOH etchant. The current-voltage char acteristics of the SIS junctions remained unchanged after the whole pr ocess, and the junctions and the membrane survived thermal cycling.