Defects, stoichiometry, and electronic transport in SrTiO{sub 3-δ} epilayers: A high pressure oxygen sputter deposition study

Journal Article · Sun Aug 07 00:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4960343· OSTI ID:22597695

Ambwani, P.; Xu, P.; Jeong, J. S.; Deng, R.; Mkhoyan, K. A.; Jalan, B.; Haugstad, G. ^[1]

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1. Characterization Facility, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

SrTiO{sub 3} is not only of enduring interest due to its unique dielectric, structural, and lattice dynamical properties, but is also the archetypal perovskite oxide semiconductor and a foundational material in oxide heterostructures and electronics. This has naturally focused attention on growth, stoichiometry, and defects in SrTiO{sub 3}, one exciting recent development being such precisely stoichiometric defect-managed thin films that electron mobilities have finally exceeded bulk crystals. This has been achieved only by molecular beam epitaxy, however (and to a somewhat lesser extent pulsed laser deposition (PLD)), and numerous open questions remain. Here, we present a study of the stoichiometry, defects, and structure in SrTiO{sub 3} synthesized by a different method, high pressure oxygen sputtering, relating the results to electronic transport. We find that this form of sputter deposition is also capable of homoepitaxy of precisely stoichiometric SrTiO{sub 3}, but only provided that substrate and target preparation, temperature, pressure, and deposition rate are carefully controlled. Even under these conditions, oxygen-vacancy-doped heteroepitaxial SrTiO{sub 3} films are found to have carrier density, mobility, and conductivity significantly lower than bulk. While surface depletion plays a role, it is argued from particle-induced X-ray emission (PIXE) measurements of trace impurities in commercial sputtering targets that this is also due to deep acceptors such as Fe at 100's of parts-per-million levels. Comparisons of PIXE from SrTiO{sub 3} crystals and polycrystalline targets are shown to be of general interest, with clear implications for sputter and PLD deposition of this important material.

• OSTI ID: 22597695
• Journal Information: Journal of Applied Physics, Vol. 120, Issue 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARRIER DENSITY
DEFECTS
DIELECTRIC MATERIALS
DOPED MATERIALS
ELECTRON MOBILITY
ENERGY BEAM DEPOSITION
LASER RADIATION
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
OXIDES
OXYGEN
PEROVSKITE
PIXE ANALYSIS
POLYCRYSTALS
PULSED IRRADIATION
SPUTTERING
STOICHIOMETRY
STRONTIUM TITANATES
THIN FILMS