First-principles study of native point defects in Bi2Se3

Using first-principles method within the framework of the density functional theory, we study the influence of native point defect on the structural and electronic properties of Bi2Se3. Se vacancy in Bi2Se3 is a double donor, and Bi vacancy is a triple acceptor. Se antisite (SeBi) is always an active donor in the system because its donor level (ɛ(+1/0)) enters into the conduction band. Interestingly, Bi antisite (BiSe1) in Bi2Se3 is an amphoteric dopant, acting as a donor when μe < 0.119 eV (the material is typical p-type) and as an acceptor when μe > 0.251 eV (the material is typical n-type). The formation energies under different growth environments (such as Bi-rich or Se-rich) indicate that under Se-rich condition, SeBi is the most stable native defect independent of electron chemical potential μe. Under Bi-rich condition, Se vacancy is the most stable native defect except for under the growth window as μe > 0.262 eV (the material is typical n-type) and ΔμSe < −0.459 eV (Bi-rich), under such growth window BiSe1 carrying one negative charge is the most stable one.