Deposition characteristics and microstructures of the high T sub c superconducting Y sub 1 Ba sub 2 Cu sub 3 O sub 7 minus. delta. thin films prepared by MOCVD

Journal Article · Mon Apr 01 00:00:00 EST 1991 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1991.0704· OSTI ID:5492211

Kim, S H; Cho, C H; No, K S; Chun, J S ^[1]

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1. Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, P. O. Box 150, Cheongryang, Seoul, Korea (KR)

Superconducting Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films were prepared on the MgO (100) and SrTiO{sub 3} (100) single crystals using metal organic chemical vapor deposition (MOCVD) of {beta}-diketone metal chelates of Y(thd){sub 3}, Ba(thd){sub 2}, and Cu(thd){sub 2}. The evaporation kinetics of Y(thd){sub 3}, Ba(thd){sub 2}, and Cu(thd){sub 2} and the ratios of deposited to evaporated mole percents of Y, Ba, and Cu cations were studied. The microstructure of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films deposited using MOCVD was observed using scanning electron microscopy and transmission electron microscopy to investigate surface morphology change with the film composition and transformation twin structures. The experimental results showed that the volatility of Ba(thd){sub 2} did not perceptively increase with decreasing evaporation pressure from 10 Torr to 5 Torr, but that of Y(thd){sub 3} or Cu(thd){sub 2} increased with the pressure decrease. The ratio of deposited to evaporated mole percents of Ba cation was smaller than those of Y and Cu cations. Therefore, Ba must be evaporated more than the stoichiometric amount for Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} in order to obtain single phase Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films. The surface morphology of the Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films showed peculiar changes with slight composition changes. The transition onset and zero resistance temperatures of typical stoichiometric film deposited on MgO were 93 K and 91 K, respectively. The Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} films had about 50 nm grain size, and most grains consisted of transformation twins. The critical current density of a film deposited on SrTiO{sub 3} was 10{sup 5} A/cm{sup 2} at 77 K and zero magnetic field.

• OSTI ID: 5492211
• Journal Information: Journal of Materials Research; (USA), Vol. 6:4; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CHEMICAL VAPOR DEPOSITION
MICROSTRUCTURE
COPPER OXIDES
YTTRIUM OXIDES
CRITICAL CURRENT
ELECTRON MICROSCOPY
FILMS
HIGH-TC SUPERCONDUCTORS
TRANSITION TEMPERATURE
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL COATING
COPPER COMPOUNDS
CRYSTAL STRUCTURE
CURRENTS
DEPOSITION
ELECTRIC CURRENTS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
SURFACE COATING
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties