Influence of charge compensation mechanisms on the sheet electron density at conducting LaAlO3/SrTiO3-interfaces

The equilibrium conductance of LaAlO3/SrTiO3 (LAO/STO)-heterointerfaces was investigated at high temperatures (950?K-1100?K) as a function of ambient oxygen partial pressure (pO2). Metallic LAO/STO-interfaces were obtained for LAO grown on STO single crystals as well as on STO-buffered (La,Sr)(Al,Ta)O3 substrates. For both structures, the high temperature sheet carrier density nS of the LAO/STO-interface saturates at a value of about 1?×?1014?cm?2 for reducing conditions, which indicates the presence of interfacial donor states. A significant decrease of nS is observed at high oxygen partial pressures. According to the defect chemistry model of donor-doped STO, this behavior for oxidizing conditions can be attributed to the formation of Sr-vacancies as charge compensating defects.

[1]  G. Rijnders,et al.  Anisotropic electrical transport properties of a two-dimensional electron gas at SrTiO3–LaAlO3 interfaces , 2011 .

[2]  T. Claeson,et al.  Improved cationic stoichiometry and insulating behavior at the interface of LaAlO3/SrTiO3 formed at high oxygen pressure during pulsed-laser deposition , 2011 .

[3]  J. Mannhart,et al.  LaAlO3/SrTiO3 oxide heterostructures studied by resonant inelastic x-ray scattering , 2010 .

[4]  R. Dittmann,et al.  Identification of A- and B-site cation vacancy defects in perovskite oxide thin films. , 2010, Physical review letters.

[5]  V. Shutthanandan,et al.  Thermodynamic instability at the stoichiometric LaAlO3/SrTiO3(001) interface , 2010, Journal of physics. Condensed matter : an Institute of Physics journal.

[6]  R. Dittmann,et al.  High temperature conductance characteristics of LaAlO3/SrTiO3-heterostructures under equilibrium oxygen atmospheres , 2010 .

[7]  J. Triscone,et al.  Influence of the growth conditions on the LaAIO3/SrTiO3 interface electronic properties , 2010 .

[8]  M. Engelhard,et al.  Instability, intermixing and electronic structure at the epitaxial LaAlO3/SrTiO3(001) heterojunction , 2010, 1006.1378.

[9]  A. Millis,et al.  Two-Dimensional Electron Gases at Oxide Interfaces , 2008 .

[10]  D. Blank,et al.  Structure–Property Relation of SrTiO3/LaAlO3 Interfaces , 2008, 0809.1068.

[11]  P. Willmott,et al.  Conducting interfaces between polar and non-polar insulating perovskites , 2008, Journal of physics. Condensed matter : an Institute of Physics journal.

[12]  K. Bouzehouane,et al.  Mapping the spatial distribution of charge carriers in LaAlO3/SrTiO3 heterostructures. , 2007, Nature materials.

[13]  R. Clarke,et al.  Structural basis for the conducting interface between LaAlO3 and SrTiO3. , 2007, Physical review letters.

[14]  W. G. van der Wiel,et al.  Magnetic effects at the interface between non-magnetic oxides. , 2007, Nature materials.

[15]  Origin of charge density at LaAlO3 on SrTiO3 heterointerfaces: possibility of intrinsic doping. , 2006, Physical review letters.

[16]  D. Muller,et al.  Why some interfaces cannot be sharp , 2005, cond-mat/0510491.

[17]  R. Moos,et al.  Defect Chemistry of Donor‐Doped and Undoped Strontium Titanate Ceramics between 1000° and 1400°C , 2005 .

[18]  Akira Ohtomo,et al.  A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface , 2004, Nature.

[19]  Donald Morgan Smyth,et al.  The Defect Chemistry of Metal Oxides , 2000 .