Title :
Fabrication and properties of Nb/MgO/Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ tunnel junctions using crystalline and amorphous MgO films grown by the MBE method
Author :
Yamano, K. ; Shimaoka, K. ; Takahashi, K. ; Usuki, T. ; Yoshisato, Y. ; Nakano, S.
Author_Institution :
Sanyo Electr. Co. Ltd., Osaka, Japan
fDate :
3/1/1993 12:00:00 AM
Abstract :
The properties of tunnel-type junctions have been improved by using the Nb/MgO/Au/BSCCO structure. Tunneling spectroscopy was examined in junctions such as Nb/MgO/BSCCO and Nb/MgO/Au/BSCCO. MgO films for tunnel barriers were grown by molecular-beam epitaxy (MBE). In a Nb/MgO/BSCCO junction with no Au layer, the superconducting gap parameters, Delta , of BSCCO single crystals with crystalline and amorphous MgO barriers were estimated to be 25 meV and 38 meV, respectively. Nb/MgO/Au/BSCCO junctions with a 20-nm-thick Au layer indicated a clear gap structure induced by the proximity effect at 30 meV. These junction characteristics were confirmed to be closely related to the existence of interdiffusion between BSCCO and other materials.<>
Keywords :
bismuth compounds; calcium compounds; chemical interdiffusion; high-temperature superconductors; magnesium compounds; niobium; proximity effect; strontium compounds; superconducting energy gap; superconducting junction devices; tunnelling spectra; HTSC; MBE; Nb-MgO-Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub x/ junctions; amorphous MgO films; crystalline MgO films; fabrication; interdiffusion; proximity effect; superconducting gap parameters; tunnel junctions; tunnelling spectroscopy; Bismuth compounds; Crystallization; Fabrication; Gold; Molecular beam epitaxial growth; Niobium; Spectroscopy; Superconducting epitaxial layers; Superconducting films; Tunneling;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
