Title :
Fabrication and tunneling measurements of YBa/sub 2/Cu/sub 3/O/sub x//CaF/sub 2//Nb thin film tunnel junctions
Author :
Tsuge, H. ; Matsukura, N.
Author_Institution :
NEC Corp., Ibaraki, Japan
fDate :
3/1/1993 12:00:00 AM
Abstract :
The heteroepitaxial growth of YBa/sub 2/Cu/sub 3/O/sub x/(YBCO)/CaF/sub 2/ has been studied and this structure has been applied to tunnel junctions. The CaF/sub 2/ thin film were epitaxially grown with [111] orientation on YBCO[110] films. The tunneling measurements of YBCO[110]/CaF/sub 2//Nb junctions exhibited that the differential conductance curves have pronounced gap-like structures with sharp peaks at the energy gap edge. The temperature dependence of the energy gap was well fitted to the scaled BCS curve. The 2 Delta /kTc of about eight was derived from the energy gap of 15 meV and T/sub c/ of 45 K obtained by the fitting. This 2 Delta /kTc value was consistent with the infrared reflectivity data reported for the direction parallel to the Cu-O planes.<>
Keywords :
Auger effect; BCS theory; X-ray diffraction examination of materials; X-ray photoelectron spectra; barium compounds; calcium compounds; electron beam deposition; energy gap; high-temperature superconductors; niobium; reflection high energy electron diffraction; reflectivity; superconducting epitaxial layers; superconducting junction devices; superconductive tunnelling; yttrium compounds; 45 K; Auger electron spectroscopy; RHEED; X-ray diffraction; X-ray photoemission spectroscopy; YBa/sub 2/Cu/sub 3/O/sub x/-CaF/sub 2/-Nb tunnel junction; [110] surface; [111] surface; differential conductance curves; electron beam guns; energy gap edge; heteroepitaxial growth; infrared reflectivity; reactive coevaporation system; scaled BCS curve; temperature dependence; thin film tunnel junctions; Electrons; Epitaxial growth; Fabrication; Niobium; Substrates; Superconductivity; Temperature; Transistors; Tunneling; Yttrium barium copper oxide;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
