A reactive coevaporation system for in situ , epitaxial YBa sub 2 Cu sub 3 O sub 7 minus x thin film deposition
- Materials Science Division, Henry Krumb School of Mines, Columbia University, New York, New York (USA)
- Bellcore, Red Bank, New Jersey (USA)
A new ultrahigh vacuum system has been specially designed and built to deposit high temperature superconducting thin films over a large area with great uniformity in both thickness and composition. The sources are in close proximity and a large distance (460 mm) separates the substrate holder and the sources. We will describe the design and the capabilities of the system including the design rationale. We have prepared {ital in} {ital situ} YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} films to demonstrate the feasibility of the system. As configured, the reactive coevaporation system can deposit up to 35 mm diam YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} films. Evaporant uniformity is expected up to 60 mm diam with the present limit in area set by the heater size, the size of the appropriate substrates, and the difficulty in attachment of substrates to the holder with uniform thermal contact. Films are prepared by coevaporation of yttrium, barium, and copper from three different evaporation sources with the substrate holder temperature measured at 680 {degree}C in a P{sub O{sub 2}}=5{times}10{sup {minus}4} Torr ambient. Because the substrate holder is 460 mm above the sources, debris from the sources cannot travel upward and stick to the film surface. Films less than 250 nm thick on (001) SrTiO{sub 3} and (001) LaAlO{sub 3} exhibit a sharp transition width ({Delta}{ital T}=0.5 K) and {ital T}{sub {ital c}}({ital R}=0)=90 K by resistivity measurements. In addition, alternating-current (ac) magnetic susceptibility characterization shows sharp transitions ({lt}1 K) at a slightly lower temperature implying that the induced screening current is uniform over the area of the detection coil. These films are structurally very close to single crystals as characterized by both x-ray diffraction and Raman scattering. thin film
- OSTI ID:
- 5295022
- Journal Information:
- Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Vol. 9:5; ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM OXIDES
VAPOR PHASE EPITAXY
COPPER OXIDES
VACUUM SYSTEMS
DESIGN
YTTRIUM OXIDES
HIGH-TC SUPERCONDUCTORS
SUPERCONDUCTING FILMS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
EPITAXY
FILMS
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication