Chalcogenide-based van der Waals epitaxy: Interface conductivity of tellurium on Si(111)

• Published in: Physical review. B 2017-07, Vol.96 (3), Article 035301
• Main Authors: Lüpke, Felix, Just, Sven, Bihlmayer, Gustav, Lanius, Martin, Luysberg, Martina, Doležal, Jiří, Neumann, Elmar, Cherepanov, Vasily, Ošt'ádal, Ivan, Mussler, Gregor, Grützmacher, Detlev, Voigtländer, Bert
• Format: Article
• Language: English
• Subjects: Chalcogenides; Conductivity; Density functional theory; Electric devices; Electrical resistivity; Epitaxy; Silicon; Structural analysis; Substrates; Tellurium; Thin films
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.96.035301

We present a combined experimental and theoretical analysis of a Te rich interface layer which represents a template for chalcogenide-based van der Waals epitaxy on Si(111). On a clean Si(111)-(1×1) surface, we find Te to form a Te/Si(111)-(1×1) reconstruction to saturate the substrate bonds. A problem arising is that such an interface layer can potentially be highly conductive, undermining the applicability of the on-top grown films in electric devices. We perform here a detailed structural analysis of the pristine Te termination and present direct measurements of its electrical conductivity by in situ distance-dependent four-probe measurements. The experimental results are analyzed with respect to density functional theory calculations and the implications of the interface termination with respect to the electrical conductivity of chalcogenide-based topological insulator thin films are discussed. In detail, we find a Te/Si(111)-(1×1) interface conductivity of σ2DTe=2.6(5)×10−7S/□, which is small compared to the typical conductivity of topological surface states.