Origin of charge density at LaAlO3 on SrTiO3 heterointerfaces: possibility of intrinsic doping

As discovered by Ohtomo and Hwang, a large sheet charge density with high mobility exists at the interface between SrTiO3 and LaAlO3. Based on transport, spectroscopic, and oxygen-annealing experiments, we conclude that extrinsic defects in the form of oxygen vacancies introduced by the pulsed laser...

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Bibliographic Details
Published in:Physical review letters 2007-05, Vol.98 (19), p.196802-196802
Main Authors: Siemons, Wolter, Koster, Gertjan, Yamamoto, Hideki, Harrison, Walter A, Lucovsky, Gerald, Geballe, Theodore H, Blank, Dave H A, Beasley, Malcolm R
Format: Article
Language:English
Subjects:
ALUMINIUM OXIDES
ANNEALING
CARRIER DENSITY
CARRIER MOBILITY
CHARGE DENSITY
INTERFACES
LANTHANUM OXIDES
MATERIALS SCIENCE
MATHEMATICAL MODELS
Other,SYNCHRAD
STRONTIUM OXIDES
TITANIUM OXIDES
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Summary:As discovered by Ohtomo and Hwang, a large sheet charge density with high mobility exists at the interface between SrTiO3 and LaAlO3. Based on transport, spectroscopic, and oxygen-annealing experiments, we conclude that extrinsic defects in the form of oxygen vacancies introduced by the pulsed laser deposition process used by all researchers to date to make these samples is the source of the large carrier densities. Annealing experiments show a limiting carrier density. We also present a model that explains the high mobility based on carrier redistribution due to an increased dielectric constant.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.98.196802