THE FABRICATION AND CHARACTERIZATION OF NBCN ALN HETEROSTRUCTURES/

Very high quality niobium nitride based superconductor - insulator - s uperconductor (SIS) junctions have been prepared using aluminium nitri de barrier layers deposited by dc reactive magnetron sputtering. These barriers have been shown to grow epitaxially on high quality epitaxia l niobium carbonitride (NbCN) base electrodes. High total gap voltages , equal to the maximum that can be expected theoretically, illustrate that there are no degraded layers at the superconductor/insulator inte rfaces. We have also demonstrated the first niobium nitride based SISI S double barrier devices. Transmission electron microscopy has been us ed to study the growth of a thick AlN layer sandwiched between NbCN an d the microstructure of NbCN/AlN multilayers prepared with several dif ferent orientation relationships.