# Polarity-field driven conductivity in SrTiO$$_3$$/LaAlO$$_3$$: A hybrid functional study

Lemal, Sebastien, Bristowe, Nicholas C., Ghosez, Philippe (2020) Polarity-field driven conductivity in SrTiO$$_3$$/LaAlO$$_3$$: A hybrid functional study. Physical Review B: Condensed Matter and Materials Physics, 102 . Article Number 115309. ISSN 0163-1829. (doi:10.1103/PhysRevB.102.115309) (KAR id:82745)

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## Abstract

The origin of the 2-dimensional electron system (2DES) appearing at the (001) interface of band insulators SrTiO$$_3$$ and LaAlO$$_3$$ has been rationalized in the framework of a polar catastrophe scenario. This implies the existence of a critical thickness of polar LaAlO$$_3$$ overlayer (4 u.c.) for the appearance of the 2DES: polar catastrophe for thick LaAlO$$_3$$ overlayer is avoided either through a Zener breakdown or a stabilization of donor defects at the LaAlO$$_3$$ surface, both providing electrons to dope the substrate. The observation of a critical thickness is observed in experiments, supporting these hypotheses. Yet, there remains an open debate about which of these possible mechanisms actually occurs first. Using hybrid functional Density Functional Theory, we re-examine these mechanisms at the same level of approximation. Particularly, we clarify the role of donor defects in these heterostructures, and argue that, under usual growth conditions, electric-field driven stabilization of oxygen vacancies and hydrogen adsorbates at the LAO surface occur at a smaller LAO thickness than required for Zener breakdown.

Item Type: Article 10.1103/PhysRevB.102.115309 Q Science > QD Chemistry Divisions > Division of Natural Sciences > School of Physical Sciences Nicholas Bristowe 03 Sep 2020 09:17 UTC 16 Feb 2021 14:14 UTC https://kar.kent.ac.uk/id/eprint/82745 (The current URI for this page, for reference purposes) https://orcid.org/0000-0003-1286-8440