Growth, characterization, and transport properties of ternary (Bi1-xSbx)2Te3 topological insulator layers

• Published in: arXiv.org 2016-10
• Main Authors: Weyrich, C, Drögeler, M, Kampmeier, J, Eschbach, M, Mussler, G, Merzenich, T, Stoica, T, Batov, I E, Schubert, J, Plucinski, L, Beschoten, B, Schneider, C M, Stampfer, C, Grützmacher, D, Schäpers, Th
• Format: Article
• Language: English
• Subjects: Antimony; Conduction bands; Crystal growth; Electrons; Epitaxial growth; Fermi level; Fermi surfaces; Molecular beam epitaxy; Photoelectric emission; Photoelectrons; Protective coatings; Raman spectroscopy; Resistance; Silicon substrates; Single crystals; Spectrum analysis; Transport properties; Valence band; X-ray diffraction
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1511.00965

Ternary (Bi1-xSbx)2Te3 films with an Sb content between 0 and 100% were deposited on a Si(111) substrate by means of molecular beam epitaxy. X-ray diffraction measurements confirm single crystal growth in all cases. The Sb content is determined by X-ray photoelectron spectroscopy. Consistent values of the Sb content are obtained from Raman spectroscopy. Scanning Raman spectroscopy reveals that the (Bi1-xSbx)2Te3 layers with an intermediate Sb content show spatial composition inhomogeneities. The observed spectra broadening in angular-resolved photoemission spectroscopy (ARPES) is also attributed to this phenomena. Upon increasing the Sb content from x=0 to 1 the ARPES measurements show a shift of the Fermi level from the conduction band to the valence band. This shift is also confirmed by corresponding magnetotransport measurements where the conductance changes from n- to p-type. In this transition region, an increase of the resistivity is found, indicating a location of the Fermi level within the band gap region. More detailed measurements in the transition region reveals that the transport takes place in two independent channels. By means of a gate electrode the transport can be changed from n- to p-type, thus allowing a tuning of the Fermi level within the topologically protected surface states.