Single-crystal growth of Nb films onto molecular beam epitaxy grown (001)InAs

Thin Nb films are grown by electron beam evaporation in an ultrahigh vacuum system on molecular beam epitaxy grown (001)InAs epitaxial layers. The Nb on InAs grows as a single-crystalline deposit at a substrate temperature of 200 °C. The orientation relation is (001)Nb//(001)InAs with [110]Nb//[110]InAs, which is different from Nb growth on GaAs. The interface between Nb and InAs features a crystal-disordered layer with a thickness of 1–2 nm, which provides relaxation from lattice mismatch. Critical current measurement of Nb/InAs/Nb junctions shows that the crystal-disordered layer does not affect the superconducting characteristics of the junctions.