Observation of surface Dirac cone in high-quality ultrathin epitaxial Bi2Se3 topological insulator on AlN(0001) dielectric.
basic_science · Level V
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- Record sourced from PubMed, PMID 24915126.
- Also identified by DOI 10.1021/nn502397x.
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Abstract
Bi2Se3 topological insulators (TIs) are grown on AlN(0001)/Si(111) substrates by molecular beam epitaxy. In a one-step growth at optimum temperature of 300 °C, Bi2Se3 bonds strongly with AlN without forming interfacial reaction layers. This produces high epitaxial quality Bi2Se3 single crystals with a perfect registry with the substrate and abrupt interfaces, allowing thickness scaling down to three quintuple layers (QL) without jeopardizing film quality. It is found by angle-resolved photoelectron spectroscopy that, remarkably, Bi2Se3 films maintain the 3D TI properties at very low thickness of 3QL (∼2.88 nm), exhibiting top surface gapless metallic states in the form of a Dirac cone.