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Surface defects and conduction in polar oxide heterostructures

Bristowe, N. C., Littlewood, P. B., Artacho, Emilio (2011) Surface defects and conduction in polar oxide heterostructures. Physical Review B, 83 (20). p. 205405. ISSN 2469-9950. (doi:10.1103/PhysRevB.83.205405) (KAR id:60263)


The polar interface between LaAlO3 and SrTiO3 has shown promise as a field effect transistor, with reduced (nanoscale) feature sizes and potentially added functionality over conventional semiconductor systems. However, the mobility of the interfacial two-dimensional electron gas (2DEG) is lower than desirable. Therefore to progress, the highly debated origin of the 2DEG must be understood. Here we present a case for surface redox reactions as the origin of the 2DEG, in particular surface O vacancies, using a model supported by first-principles calculations that describes the redox formation. In agreement with recent spectroscopic and transport measurements, we predict a stabilization of such redox processes (and hence Ti 3d occupation) with film thickness beyond a critical value, which can be smaller than the critical thickness for 2D electronic conduction, since the surface defects generate trapping potentials that will affect the interface electron mobility. Several other recent experimental results, such as lack of core-level broadening and shifts, find a natural explanation. Pristine systems will likely require changed growth conditions or modified materials with a higher vacancy free energy.

Item Type: Article
DOI/Identification number: 10.1103/PhysRevB.83.205405
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QC Physics > QC176 Solid state physics
Q Science > QD Chemistry > QD478 Solid State Chemistry
Q Science > QC Physics > QC176.8.N35 Nanoscience, nanotechnology
Q Science > QD Chemistry > QD473 Physical properties in relation to structure
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Depositing User: Nicholas Bristowe
Date Deposited: 21 Feb 2017 15:30 UTC
Last Modified: 16 Nov 2021 10:24 UTC
Resource URI: (The current URI for this page, for reference purposes)

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