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arXiv · 1212.5947

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

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.

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A. Janotti, L. Bjaalie, L. Gordon, C. G. Van de Walle. 2012-12-24. Controlling the density of the 2DEG at the SrTiO3/LaAlO3 interface. https://doi.org/10.1103/physrevb.86.241108

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