Preparation of superconducting epitaxial thin films of transition metal nitrides on silicon wafers by molecular beam epitaxy

Epitaxial thin films of NbN and CrN on Si substrates were prepared by molecular beam epitaxy (MBE) and were characterized by X-ray diffraction. X-ray diffraction pole figure measurements, atomic force microscopy (AFM), and magnetic measurements. To our knowledge, CrN was growth epitaxially on Si substrates for the first time. Although lattice parameters of CrN and Si are significantly different, the epitaxial growth of CrN on Si(1 0 0) was explained by a good fitting of 4 unit cells of CrN to 3 unit cells of Si(misfit: 1.7%). NbN was found to grow epitaxially by using CrN as a buffer layer on Si(1 0 0), and this film was superconducting below 4.5 K. A CrN/NbN/CrN epitaxial sandwich structure was also prepared successfully, indicating that the NbN-CrN system is promising for superlattices of superconductor and insulator fabricated on Si substrate. (C) 2002 Elsevier Science B.V. All rights reserved.