Epitaxy of polar semiconductor Co{sub 3}O{sub 4} (110): Growth, structure, and characterization

Journal Article · Sat Jun 28 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4885048· OSTI ID:22304489

Kormondy, Kristy J.; Posadas, Agham B.; Slepko, Alexander; Dhamdhere, Ajit; Smith, David J. ^[1]; Mitchell, Khadijih N.; Willett-Gies, Travis I.; Zollner, Stefan ^[2]; Marshall, Luke G.; Zhou, Jianshi ^[3]

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1. Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)
2. Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003 (United States)
3. Materials Science and Engineering Program/Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States)

The (110) plane of Co{sub 3}O{sub 4} spinel exhibits significantly higher rates of carbon monoxide conversion due to the presence of active Co{sup 3+} species at the surface. However, experimental studies of Co{sub 3}O{sub 4} (110) surfaces and interfaces have been limited by the difficulties in growing high-quality films. We report thin (10–250 Å) Co{sub 3}O{sub 4} films grown by molecular beam epitaxy in the polar (110) direction on MgAl{sub 2}O{sub 4} substrates. Reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and transmission electron microscopy measurements attest to the high quality of the as-grown films. Furthermore, we investigate the electronic structure of this material by core level and valence band x-ray photoelectron spectroscopy, and first-principles density functional theory calculations. Ellipsometry reveals a direct band gap of 0.75 eV and other interband transitions at higher energies. A valence band offset of 3.2 eV is measured for the Co{sub 3}O{sub 4}/MgAl{sub 2}O{sub 4} heterostructure. Magnetic measurements show the signature of antiferromagnetic ordering at 49 K. FTIR ellipsometry finds three infrared-active phonons between 300 and 700 cm{sup −1}.

• OSTI ID: 22304489
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETISM
ATOMIC FORCE MICROSCOPY
CARBON MONOXIDE
COBALT OXIDES
CRYSTAL STRUCTURE
DENSITY FUNCTIONAL METHOD
ELECTRON DIFFRACTION
ELECTRONIC STRUCTURE
ELLIPSOMETRY
ENERGY-LEVEL TRANSITIONS
FILMS
FOURIER TRANSFORM SPECTROMETERS
INTERFACES
MOLECULAR BEAM EPITAXY
SEMICONDUCTOR MATERIALS
SUBSTRATES
SURFACES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY