Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface

A. Janotti; L. Bjaalie; L. Gordon; C. G. Van de Walle

doi:10.1103/PhysRevB.86.241108

Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface

Materials Science 2015-06-12 v1

Authors: A. Janotti , L. Bjaalie , L. Gordon , C. G. Van de Walle

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Abstract

The polar discontinuity at the SrTiO3/LaAlO3 interface (STO/LAO) can in principle sustain an electron density of 3.3E14 cm-2 (0.5 electrons per unit cell). However, experimentally observed densities are more than an order of magnitude lower. Using a combination of first-principles and Schrodinger-Poisson simulations we show that the problem lies in the asymmetric nature of the structure, i.e., the inability to form a second LAO/STO interface that is a mirror image of the first, or to fully passivate the LAO surface. Our insights apply to oxide interfaces in general, explaining for instance why the SrTiO3/GdTiO3 interface has been found to exhibit the full density of 3.3E14 cm-2.

Keywords

2DEG SrTiO3/LaAlO3 interface polar discontinuity electron density first-principles simulations Schrödinger-Poisson simulations oxide interfaces surface passivation

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@article{arxiv.1212.5947,
  title  = {Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface},
  author = {A. Janotti and L. Bjaalie and L. Gordon and C. G. Van de Walle},
  journal= {arXiv preprint arXiv:1212.5947},
  year   = {2015}
}

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5 pages, 3 figures

Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface

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