Atomic layer deposition of photoactive CoO/SrTiO{sub 3} and CoO/TiO{sub 2} on Si(001) for visible light driven photoelectrochemical water oxidation

Journal Article · Wed Aug 28 04:00:00 EDT 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4819106· OSTI ID:22218107

Ngo, Thong Q.; Hoang, Son; McDaniel, Martin D.; Buddie Mullins, C.; Ekerdt, John G. ^[1]; Posadas, Agham; Seo, Hosung; Demkov, Alexander A. ^[2]; Utess, Dirk; Triyoso, Dina H. ^[3]

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1. Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States)
2. Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)
3. GLOBALFOUNDRIES Dresden, Wilschdorfer Landstrasse 101, Dresden DE-01109 (Germany)

Cobalt oxide (CoO) films are grown epitaxially on Si(001) by atomic layer deposition (ALD) using a thin (1.6 nm) buffer layer of strontium titanate (STO) grown by molecular beam epitaxy. The ALD growth of CoO films is done at low temperature (170–180 °C), using cobalt bis(diisopropylacetamidinate) and water as co-reactants. Reflection high-energy electron diffraction, X-ray diffraction, and cross-sectional scanning transmission electron microscopy are performed to characterize the crystalline structure of the films. The CoO films are found to be crystalline as-deposited even at the low growth temperature with no evidence of Co diffusion into Si. The STO-buffered Si (001) is used as a template for ALD growth of relatively thicker epitaxial STO and TiO{sub 2} films. Epitaxial and polycrystalline CoO films are then grown by ALD on the STO and TiO{sub 2} layers, respectively, creating thin-film heterostructures for photoelectrochemical testing. Both types of heterostructures, CoO/STO/Si and CoO/TiO{sub 2}/STO/Si, demonstrate water photooxidation activity under visible light illumination. In-situ X-ray photoelectron spectroscopy is used to measure the band alignment of the two heterojunctions, CoO/STO and CoO/TiO{sub 2}. The experimental band alignment is compared to electronic structure calculations using density functional theory.

• OSTI ID: 22218107
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 114; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COBALT OXIDES
DENSITY FUNCTIONAL METHOD
ELECTRON DIFFRACTION
MOLECULAR BEAM EPITAXY
STRONTIUM
STRONTIUM TITANATES
THIN FILMS
TITANIUM OXIDES
TRANSMISSION ELECTRON MICROSCOPY
WATER
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY