Transport properties in a Sb-Te binary topological-insulator system

• Published in: Journal of physics. Condensed matter Vol. 25; no. 34; p. 345801
• Main Authors: Takagaki, Y, Giussani, A, Tominaga, J, Jahn, U, Calarco, R
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 28.08.2013; Institute of Physics
• Subjects: Adjustable; Antimony; Binary systems; Bistability; Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Density; Electronic transport in condensed matter; Exact sciences and technology; Galvanomagnetic and other magnetotransport effects; Insulators; Physics; Reduction; Topological insulator; Energy gap; Acceptor center; Magnetic field effects; Molecular beam epitaxy; Density functional method; Transport processes; Magnetoresistance; Antimony tellurides; Bistability; Crystal structure
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/25/34/345801

Sb-Te layers having various compositions between Sb2Te3 and Sb2Te are grown using molecular beam epitaxy. The structural and electrical properties of the layers change gradually with composition but exhibit a discontinuity involving a bistability. The holes in the layers are generated by Sb bilayers intercalated between Sb2Te3 quintuple layers and their mobility is governed by the scattering from the parent acceptors. Magnetoresistance for compositions around SbTe is linear, for which the reduction of the parabolic component due to low mobility is crucial. Density functional calculations predict Sb2Te3 and SbTe to be topological insulators (TIs) resembling Bi2Se3 and Bi2Te3, respectively. The prefactor of the weak antilocalization effect is α =− 1 regardless of the composition. The Sb-Te system is thus a family of TIs possessing undisturbed surface states for which the location of the Dirac point with respect to the bulk band gap is adjustable.