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Fabrication of Epitaxial Films of Electron-Doped Cuprate Superconductors

IP.com Disclosure Number: IPCOM000100313D
Original Publication Date: 1990-Apr-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Gupta, A: AUTHOR [+3]

Abstract

Disclosed is a process for depositing epitaxial film of the electron-doped superconductors, such as Lnz-xCexCuO4-y (Ln = Nd, Pr or Sm,x Z 0.15, y Z 0.02) by the technique of laser ablation (*). Also disclosed is a process for controlling the oxygen-content of the deposited films by thermal annealing to achieve superconductivity with Tc Z 20K. The films were deposited on optically polished (100) SrTiO3 substrates which were glued with silver paint to a holder which could be resistively heated up to 900oC. Most of the films were deposited at a substrate temperature of 780oC in the presence of 150 mTorr pressure of oxygen in the chamber. The deposited films were then left at the deposition temperature and the deposition chamber was pumped down to <10-5 Torr.

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Fabrication of Epitaxial Films of Electron-Doped Cuprate Superconductors

       Disclosed is a process for depositing epitaxial film of
the electron-doped superconductors, such as Lnz-xCexCuO4-y (Ln = Nd,
Pr or Sm,x Z 0.15, y Z 0.02) by the technique of laser ablation (*).
Also disclosed is a process for controlling the oxygen-content of the
deposited films by thermal annealing to achieve superconductivity
with Tc Z 20K.  The films were deposited on optically polished (100)
SrTiO3 substrates which were glued with silver paint to a holder
which could be resistively heated up to 900oC.  Most of the films
were deposited at a substrate temperature of 780oC in the presence of
150 mTorr pressure of oxygen in the chamber. The deposited films were
then left at the deposition temperature and the deposition chamber
was pumped down to <10-5 Torr.  The amount of oxygen which can be
removed from the films depends on the temperature and time during
which the films are left in the vacuum and also on their thickness.
Resistivity versus temperature results of three 2500 Ao films
deposited at a substrate temperature of 780oC in 150 mTorr O2
ambient, and then vacuum annealed for different durations (A. 10 min.
B. 45 min. C. 90 min.), are shown in the figure.  The best film, with
optimum reduction, shows an onset temperature of 21K and Tc (R = 0) N
20K.  The zero-field critical current density (Jc) of this film
increases sharply with decreasing temperature and reaches a value of
2 x...