Title :
In-situ sputtering of YBCO films for microwave applications
Author :
Ballentine, H. ; Kadin, A.M. ; Mallory, D.S.
Author_Institution :
CVC Products Inc., Rochester, NY, USA
fDate :
3/1/1991 12:00:00 AM
Abstract :
RF magnetron sputtering from a single YBCO target onto a heated substrate (≈700°C) was used to obtain c-axis-oriented 1-2-3 films that are superconducting without a subsequent annealing or oxygenation step, with Tc(R=0) as high as 88 K on MgO and LaAlO 3 substrates. This process uses an 8-in-diameter target in the sputter-up configuration, with a central grounded shield to eliminate negative ion bombardment. It can reproducibly and uniformly cover substrates as large as 3-in across at rates exceeding 1 Å/s. Maintaining film composition very close to stoichiometry is essential for obtaining films with good superconducting properties and surface morphology. Optimum films have critical currents of ≈1 MA/cm2 at 77 K. Measurements of microwave surface resistance based on a stripline resonator indicate low surface resistance for unpatterned YBCO ground planes, but excess loss and a strong power dependence in a patterned center strip
Keywords :
barium compounds; critical currents; high-temperature superconductors; sputter deposition; superconducting thin films; yttrium compounds; 700 degC; 88 K; LaAlO3; MgO; RF magnetron sputtering; Y-Ba-Cu-O; c-axis-oriented; composition; critical currents; films; ground planes; heated substrate; high temperature superconductors; in situ sputtering; microwave applications; microwave surface resistance; stoichiometry; stripline resonator; superconducting properties; surface morphology; Electromagnetic heating; Radio frequency; Sputtering; Substrates; Superconducting films; Superconducting magnets; Superconducting microwave devices; Surface morphology; Surface resistance; Yttrium barium copper oxide;
Journal_Title :
Magnetics, IEEE Transactions on
