Probing vacancy behavior across complex oxide heterointerfaces.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30801011.
- Also identified by DOI 10.1126/sciadv.aau8467 and PMC identifier 6386560.
- Licence recorded as CC BY-NC.
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Abstract
Oxygen vacancies ( <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow> <mrow><msubsup><mi>V</mi> <mi>O</mi> <mrow><mo>•</mo> <mo>•</mo></mrow> </msubsup> </mrow> </mrow> </math> ) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO<sub>3</sub> (Nb:SrTiO<sub>3</sub>) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using (<i>T</i> = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate.