How heteroepitaxy occurs on strontium titanate.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30993200.
- Also identified by DOI 10.1126/sciadv.aav0764 and PMC identifier 6461459.
- Licence recorded as CC BY-NC.
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Abstract
In traditional models of heteroepitaxy, the substrate serves mainly as a crystalline template for the thin-film lattice, dictating the initial roughness of the film and the degree of coherent strain. Here, performing in situ surface x-ray diffraction during the heteroepitaxial growth of LaTiO<sub>3</sub> on SrTiO<sub>3</sub> (001), we find that a TiO<sub>2</sub> adlayer composed of the <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><mrow><mo>(</mo> <msqrt><mn>13</mn></msqrt> <mo>×</mo> <msqrt><mn>13</mn></msqrt> <mo>)</mo></mrow> </mrow> </math> <i>R</i>33.7° and <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><mrow><mo>(</mo> <msqrt><mn>2</mn></msqrt> <mo>×</mo> <msqrt><mn>2</mn></msqrt> <mo>)</mo></mrow> </mrow> </math> <i>R</i>45.0° reconstructions is a highly active participant in the growth process, continually diffusing to the surface throughout deposition. The effects of the TiO<sub>2</sub> adlayer on layer-by-layer growth are investigated using different deposition sequences and anomalous x-ray scattering, both of which permit detailed insight into the dynamic layer rearrangements that take place. Our work challenges commonly held assumptions regarding growth on TiO<sub>2</sub>-terminated SrTiO<sub>3</sub> (001) and demonstrates the critical role of excess TiO<sub>2</sub> surface stoichiometry on the initial stages of heteroepitaxial growth on this important perovskite oxide substrate material.