Electronic band structure of Sb2Te3

Abstract

We report on Landau-level spectroscopy of an epitaxially grown thin film of the topological insulator Sb(2)Te(3), complemented by ellipsometry and magnetotransport measurements. The observed response suggests that Sb(2)Te(3) is a direct-gap semiconductor with the fundamental band gap located at the gamma point or along the trigonal axis, and its width reaches E(g) = (190 +/- 10) meV at low temperatures. Our data also indicate the presence of other low-energy extrema with a higher multiplicity in both the conduction and valence bands. The conclusions based on our experimental data are confronted with and to a great extent corroborated by the electronic band structure calculated using the GW method.