First Principle Study of Defect Induced Band Structure in Cu Substituted Bi2Te3 Topological Insulator

This paper deals with the Cu substituted Bi2Te3 topological insulator's electronic band structure and its defect induced behavior. The pristine Bi2Te3 compound has a unique band structure, where the bulk band is semiconducting and the surface band is metallic. However, here, we report the modulation of the bulk-band structure with the injection of Cu atoms in the pristine Bi2Te3 compound. Our ab initio simulation reveals that 5 at.% of Cu substitution in Bi site transforms the electronic ground state of Bi2Te3 to a p-type one. In contrast, the intercalation of Cu atoms by a similar amount turns the electronic ground state of Bi2Te3 into an n-type one. We have also discussed the band structure of the carrier-compensated configuration of the Cu substituted Bi2Te3 compound with the creation of Te vacancy. Our simulation gives an excellent agreement with the experimentally.