A NEW FABRICATION METHOD OF ULTRA-SMALL TUNNEL-JUNCTIONS

A new fabrication method of micro-structures is described. Using a Si3 N4 membrane having small windows as a mask, a metal film of fine struc tures are vacuum-deposited directly onto a substrate. By means of piez o-electric actuators or of double-angle evaporation, small tunnel-junc tions are formed. This method has an important advantages, that is, th e lift-off process after vacuum-deposition is not needed, and the plas ma oxidation can be used for making tunnel barriers. We fabricated tun nel-junction arrays made of ferromagnetic metals, which showed both th e Coulomb blockade and the magnetic valve effect at low temperatures.