Volume 93, Number 3, February 2011
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||10 February 2011|
Improved cationic stoichiometry and insulating behavior at the interface of LaAlO3/SrTiO3 formed at high oxygen pressure during pulsed-laser deposition
Department of Microtechnology and Nanoscience - MC2, Chalmers University of Technology Göteborg, Sweden, EU
2 Ioffe Physico-Technical Institute RAS - St. Petersburg, Russia
3 Department of Applied Physics, Chalmers University of Technology - Göteborg, Sweden, EU
4 Skobeltsyn Institute of Nuclear Physics, Moscow State University - Moscow, Russia
Accepted: 17 January 2011
Medium-energy ion spectroscopy, MEIS, and scanning transmission electron microscopy, STEM, were used to correlate the atomic structure of LaAlO3/SrTiO3 interfaces with their electrical properties. Interfaces were prepared at high (5×10−2 mbar) and low (10−4 mbar) oxygen pressure by pulsed-laser deposition. The high-oxygen-pressure heterostructures were insulating for all thicknesses while the low-oxygen-pressure ones became metallic for thicknesses above 4 unit cells. MEIS data show enhancement of the Sr surface peak and suppression of the La one in interfaces prepared at low oxygen pressure, which is interpreted as a La-Sr intermixing. The effect was considerably smaller in high-oxygen-pressure samples. Analysis of high-angle annular-dark-field STEM images of the LAO films also indicates intermixing between La and Sr in low-oxygen-pressure samples, supporting MEIS data. Our results reveal the important role of oxygen pressure on the formation of the interface electron gas.
PACS: 73.20.-r – Electron states at surfaces and interfaces / 73.21.Ac – Multilayers / 73.40.-c – Electronic transport in interface structures
© EPLA, 2011
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