Epitaxial, Silicon-Compatible CoSi₂ Thin Film SQUID with Constriction-Type Junction

Abstract

Transition metal silicides are widely used in integrated circuits as contacts and interconnect. $ {CoSi_2} $ has superconducting $ {T_c} $ of 1.4 K and lattice mismatch to Si of 1.2%, thus making it promising for integrating silicon technology into superconducting device fabrication. Here we demonstrate the growth of epitaxial $ {CoSi_2} $ thin film on Si(111) substrate and the fabrication of a constriction-type superconducting quantum interference device (SQUID) by silicidation of Co metal on the silicon substrate. The $ {CoSi_2} $ -Si interface shows $ {CoSi_2} \ (111) $ // Si(111) epitaxy, with in-plane texture $ {CoSi_2} \ (100) $ // Si(111) and $ {CoSi_2 \ (110)} $ // Si(111). The fabricated SQUID has a superconducting loop area of 0.8 μm2, the oscillating critical current with the applied magnetic field typical for SQUID is observed with $ {φ_0} $ = 1.3 mT. The junction resistance of constriction-type SQUID is calculated to be linear with device channel length.