Electronic band structure of three-dimensional topological insulators with different stoichiometry composition

We report on a comparative theoretical and experimental investigation of the electronic band structure of a family of three-dimensional topological insulators, A(IV)Bi(4)Te(7-x)Se(x) (A(IV) = Sn, Pb; x = 0, 1). We prove by means of density functional theory calculations and angle-resolved photoemission spectroscopy measurements that partial or total substitution of heavy atoms by lighter isoelectronic ones affects the electronic properties of topological insulators. In particular, we show that the modification of the Dirac cone position relative to the Fermi level and the bulk band gap size can be controlled by varying the stoichiometry of the compound. We also demonstrate that the investigated systems are inert to oxygen exposure.