Interface and Electronic Characterization of Thin Epitaxial Co3O4 Films
The interface and electronic structure of thin ({approx} 20-74 nm) Co{sub 3}O{sub 4}(1 1 0) epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl{sub 2}O{sub 4}(1 1 0) single crystal substrates have been investigated by means of real and reciprocal space techniques. As-grown film surfaces are found to be relatively disordered and exhibit an oblique low energy electron diffraction (LEED) pattern associated with the O-rich CoO{sub 2} bulk termination of the (1 1 0) surface. Interface and bulk film structure are found to improve significantly with post-growth annealing at 820 K in air and display sharp rectangular LEED patterns, suggesting a surface stoichiometry of the alternative Co{sub 2}O{sub 2} bulk termination of the (1 1 0) surface. Non-contact atomic force microscopy demonstrates the presence of wide terraces separated by atomic steps in the annealed films that are not present in the as-grown structures; the step height of {approx}2.7 {angstrom} corresponds to two atomic layers and confirms a single termination for the annealed films, consistent with the LEED results. A model of the (1 x 1) surfaces that allows for compensation of the polar surfaces is presented.
- Research Organization:
- Brookhaven National Laboratory (BNL) Center for Functional Nanomaterials
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1040087
- Report Number(s):
- BNL--90240-2009-JA; KC020401H
- Journal Information:
- Surface Science, Journal Name: Surface Science Journal Issue: 2 Vol. 603; ISSN SUSCAS; ISSN 0039-6028
- Country of Publication:
- United States
- Language:
- English
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