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Oxygen Vacancies at the γ-Al2O3/STO Heterointerface Grown by Atomic Layer Deposition

Published online by Cambridge University Press:  19 March 2015

Thong Q. Ngo ,
Martin D. McDaniel ,
Agham Posadas ,
Alexander A. Demkov  and
John G. Ekerdt
Thong Q. Ngo
Affiliation:
Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, U.S.A.
Martin D. McDaniel
Affiliation:
Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, U.S.A.
Agham Posadas
Affiliation:
Department of Physics, University of Texas at Austin, Austin, Texas 78712, U.S.A.
Alexander A. Demkov
Affiliation:
Department of Physics, University of Texas at Austin, Austin, Texas 78712, U.S.A.
John G. Ekerdt
Affiliation:
Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, U.S.A.
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Abstract

We report the epitaxial growth of γ-Al2O3 on SrTiO3 (STO) substrates by atomic layer deposition (ALD). The ALD growth of γ-Al2O3 on STO(001) single crystal substrates was performed at a temperature of 345 °C. Trimethylaluminum and water were used as co-reactants. In-situ reflection high-energy electron diffraction and ex-situ x-ray diffraction were used to determine the crystallinity of the Al2O3 films. In-situ x-ray photoelectron spectroscopy was used to characterize the Al2O3/STO heterointerface. The formation of a Ti3+ feature is observed in the Ti 2p spectrum of STO after the first few ALD cycles of Al2O3 and even after exposure of the STO substrate to trimethylaluminum alone at 345 °C. The presence of a Ti3+ feature is a direct indication of oxygen vacancies at the Al2O3/STO heterointerface, which provide the carriers for the quasi-two dimensional electron gas at the interface.

Keywords

atomic layer depositionx-ray photoelectron spectroscopy (XPS)epitaxy
Type
Articles
Information
MRS Online Proceedings Library (OPL) , Volume 1730: Symposium N – Frontiers in Complex Oxides , 2015 , mrsf14-1730-n08-06
Copyright
Copyright © Materials Research Society 2015 

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