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

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.
Authors:
; ; ; ;  [1] ; ; ;  [2] ; ;  [3]
  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)
Publication Date:
OSTI Identifier:
22218107
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
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