Title :
Influence of deposition parameters on properties of laser ablated YBa/sub 2/Cu/sub 3/O/sub 7- delta / films
Author :
Roshko, A. ; Rudman, D.A. ; Vale, L.R. ; Goodrich, L.F. ; Moreland, J. ; Beck, H.L.
Author_Institution :
Nat. Inst. of Stand. & Technol., Boulder, CO, USA
fDate :
3/1/1993 12:00:00 AM
Abstract :
YBa/sub 2/Cu/sub 3/O/sub 7- delta / films have been laser ablated, under a variety of conditions, onto four different substrate materials. Using scanning tunneling microscopy it was observed that the films grow by an island nucleation and growth mechanism. The properties of the films were studied as functions of the deposition conditions. Films on LaAlO/sub 3/ had the best and most reproducible properties. The superconducting transition temperatures of films deposited on LaAlO/sub 3/ proved to be fairly insensitive to the substrate temperature during deposition; T/sub c/´s>90 K were obtained for films deposited over a temperature range from 760 degrees C to 850 degrees C. The oxygen partial pressure during the deposition had a large effect on the transition temperature; the highest T/sub c/´s were obtained for films deposited in 26.7-Pa (200-mTorr) oxygen. Measurements of transport critical current indicate that films deposited at lower temperatures are less sensitive to magnetic fields, suggesting that they may contain more defects which act as flux pinning sites.<>
Keywords :
barium compounds; critical current density (superconductivity); flux pinning; high-temperature superconductors; pulsed laser deposition; scanning tunnelling microscopy; superconducting thin films; superconducting transition temperature; yttrium compounds; 26.7 Pa; 760 to 850 C; LaAlO/sub 3/ substrate; MgO; O/sub 2/ partial pressure; SrTiO/sub 3/; Y/sub 2/O/sub 3/-ZrO/sub 2/; YBa/sub 2/Cu/sub 3/O/sub 7- delta /; deposition conditions; deposition parameters; flux pinning sites; growth mechanism; island nucleation; laser ablated films; scanning tunneling microscopy; substrate materials; substrate temperature; superconducting transition temperatures; transport critical current; Magnetic field measurement; Magnetic films; Microscopy; Optical materials; Superconducting films; Superconducting materials; Superconducting transition temperature; Temperature distribution; Temperature sensors; Tunneling;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
