INVESTIGADORES
SIRENA Martin
artículos
Título:
Technology optimizations for Giaever transformer
Autor/es:
R. BERNARD; J. BRIATICO; M. SIRENA; D. G. CRéTé; J. P. CONTOUR; F. WYCZICK; J. SIEJKA
Revista:
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
Referencias:
Año: 2007 p. 3589 - 3592
ISSN:
1051-8223
Resumen:
AbstractIn this paper, we present several steps in the
development of an HTS Giaever transformer, based on a SIS
heterostructure, where both superconducting thin film should
present low pinning properties and be insulated with a thin
insulating layer. High Resolution AC Susceptibility measurements
on YBCO//STO and NBCO//STO thin films show that the most
important pinning centers are twin boundary intersections (TBI),
and that their elimination with proper growth conditions allows
to improve vortex mobility. When the base layer outgrowth
density exceeds 105/cm2, pinholes through the insulating layer
(PBCO/STO) short-circuit the electrodes. Therefore, ion beam
milling at grazing incidence has been performed to reduce the
height of the outgrowths otherwise protruding between 0.5 and
1.5 ìm above the surface of the film. We could reduce their
density by 10 and barrier leakage by 1000 with only 10nm of
insulator thickness. Several Giaever devices were fabricated with
this ion milling process and by ajusting the regrowth temperature.
The influence of this new technology was investigated: AES
analysis indicates a preferential erosion of copper ions, a damaged
surface layer of 5nm is deduced from RBS analysis.In this paper, we present several steps in the
development of an HTS Giaever transformer, based on a SIS
heterostructure, where both superconducting thin film should
present low pinning properties and be insulated with a thin
insulating layer. High Resolution AC Susceptibility measurements
on YBCO//STO and NBCO//STO thin films show that the most
important pinning centers are twin boundary intersections (TBI),
and that their elimination with proper growth conditions allows
to improve vortex mobility. When the base layer outgrowth
density exceeds 105/cm2, pinholes through the insulating layer
(PBCO/STO) short-circuit the electrodes. Therefore, ion beam
milling at grazing incidence has been performed to reduce the
height of the outgrowths otherwise protruding between 0.5 and
1.5 ìm above the surface of the film. We could reduce their
density by 10 and barrier leakage by 1000 with only 10nm of
insulator thickness. Several Giaever devices were fabricated with
this ion milling process and by ajusting the regrowth temperature.
The influence of this new technology was investigated: AES
analysis indicates a preferential erosion of copper ions, a damaged
surface layer of 5nm is deduced from RBS analysis.5/cm2, pinholes through the insulating layer
(PBCO/STO) short-circuit the electrodes. Therefore, ion beam
milling at grazing incidence has been performed to reduce the
height of the outgrowths otherwise protruding between 0.5 and
1.5 ìm above the surface of the film. We could reduce their
density by 10 and barrier leakage by 1000 with only 10nm of
insulator thickness. Several Giaever devices were fabricated with
this ion milling process and by ajusting the regrowth temperature.
The influence of this new technology was investigated: AES
analysis indicates a preferential erosion of copper ions, a damaged
surface layer of 5nm is deduced from RBS analysis.ìm above the surface of the film. We could reduce their
density by 10 and barrier leakage by 1000 with only 10nm of
insulator thickness. Several Giaever devices were fabricated with
this ion milling process and by ajusting the regrowth temperature.
The influence of this new technology was investigated: AES
analysis indicates a preferential erosion of copper ions, a damaged
surface layer of 5nm is deduced from RBS analysis.