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

Transition metal silicides are widely used in integrated circuits as contacts and interconnect. CoSi₂ 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 CoSi₂ 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 CoSi₂ -Si interface shows CoSi₂ (111) // Si(111) epitaxy, with in-plane texture CoSi₂ (100) // Si(111) and CoSi₂(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 φ₀ = 1.3 mT. The junction resistance of constriction-type SQUID is calculated to be linear with device channel length.