Dichotomy of the photo-induced 2-dimensional electron gas on SrTiO<sub>3</sub> surface terminations.
basic_science · Level V
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- Record sourced from PubMed, PMID 31391304.
- Also identified by DOI 10.1073/pnas.1821937116 and PMC identifier 6708339.
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Abstract
Oxide materials are important candidates for the next generation of electronics due to a wide array of desired properties, which they can exhibit alone or when combined with other materials. While SrTiO<sub>3</sub> (STO) is often considered a prototypical oxide, it, too, hosts a wide array of unusual properties, including a 2-dimensional electron gas (2DEG), which can form at the surface when exposed to ultraviolet (UV) light. Using layer-by-layer growth of high-quality STO films, we show that the 2DEG only forms with the SrO termination and not with the TiO<sub>2</sub> termination, contrary to expectation. This dichotomy of the observed angle-resolved photoemission spectroscopy (ARPES) spectra is similarly seen in BaTiO<sub>3</sub> (BTO), in which the 2DEG is only observed for BaO-terminated films. These results will allow for a deeper understanding and better control of the electronic structure of titanate films, substrates, and heterostructures.