A study of Y--Ba--Cu--O/Si interfaces by x-ray photoelectron spectroscopy

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)

DOI:https://doi.org/10.1116/1.578123· OSTI ID:5526605

Chourasia, A R; Chopra, D R ^[1]; Bensaoula, A H; Bensaoula, A; Ruzakowski, P ^[2]

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1. Department of Physics, East Texas State University, Commerce, Texas 75429 (United States)
2. Space Vacuum Epitaxy Center, Physics Department, University of Houston, Houston, Texas 77204-5507 (United States)

Thin films ({similar to}300 A) of the superconductor YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital y}} were deposited on a Si {l angle}100{r angle} substrate by molecular beam epitaxy. The sample was then cleaved in two pieces and one of these was annealed at 860 {degree}C for 3 h. X-ray photoelectron spectroscopy in conjunction with sputter depth-profiling was utilized to study the interfaces in the unannealed and the annealed samples. Such a comparative study minimizes problems inherent to sputtering. The Y 3{ital d}, Ba 3{ital d}, Cu 2{ital p}, O 1{ital s}, and Si 2{ital p} regions were investigated. In the unannealed sample, Si diffuses into the constituents of the superconductor near the interface. Oxygen is found to be depleted from the CuO planes in the superconductor thin film with the formation of silicon suboxide. Also, the interface is narrow. In the annealed sample, Si diffuses extensively into the constituents of the superconductor. The Cu--O bonds are broken with the formation of SiO{sub 2}. This SiO{sub 2} is detected on the surface of the sample. At a depth of 450 A in the sample, Ba--O bonds are also broken partially and some Si suboxide is formed. Because of the extensive interdiffusion, the interface in this sample is broad. It is found that in both cases, Cu--O bonds are broken with oxygen used mainly in the formation of silicon oxides. The study shows that significant interdiffusion occurs at Si/superconductor interface during the high temperature anneal necessary to form the superconductor phase. It is concluded that oxidation of Si at the expense of copper and not the diffusion of Si into the superconductor is responsible for the degradation of performance of the superconductor thin film. Consequently, a suitable diffusion barrier which allows elevated temperature during deposition or annealing stages would be required in the fabrication of superconductor/Si devices.

• OSTI ID: 5526605
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States), Vol. 10:1, Issue 1; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
ANNEALING
MOLECULAR BEAM EPITAXY
COPPER OXIDES
SILICON
DIFFUSION
YTTRIUM OXIDES
ATOM TRANSPORT
CHEMICAL BONDS
ELECTRONIC STRUCTURE
INTERFACES
PHOTOELECTRON SPECTROSCOPY
SPUTTERING
SUPERCONDUCTING FILMS
X RADIATION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ELEMENTS
EPITAXY
FILMS
HEAT TREATMENTS
IONIZING RADIATIONS
NEUTRAL-PARTICLE TRANSPORT
OXIDES
OXYGEN COMPOUNDS
RADIATION TRANSPORT
RADIATIONS
SEMIMETALS
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360204* - Ceramics
Cermets
& Refractories- Physical Properties
360207 - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)