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.