paper

First-principles study of native point defects in Bi2Se3

arXiv:1207.0103

Abstract

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 Bi $_{2}$ Se $_{3}$ . Se vacancy in Bi $_{2}$ Se $_{3}$ is a double donor, and Bi vacancy is a triple acceptor. Se antisite (Se $_{B i}$ ) is always an active donor in the system because its donor level ( $ε$ (+1/0)) enters into the conduction band. Interestingly, Bi antisite(Bi $_{S e 1}$ ) in Bi $_{2}$ Se $_{3}$ is an amphoteric dopant, acting as a donor when $I^¼$ $_{e}$ $<$ 0.119eV (the material is typical p-type) and as an acceptor when $I^¼$ $_{e}$ $>$ 0.251eV (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, Se $_{B i}$ is the most stable native defect independent of electron chemical potential $I^¼$ $_{e}$ . Under Bi-rich condition, Se vacancy is the most stable native defect except for under the growth window as $I^¼$ $_{e}$ $>$ 0.262eV (the material is typical n-type) and $I^$ $I^¼$ $_{S e}$ $<$ -0.459eV(Bi-rich), under such growth windows one negative charged Bi $_{S e 1}$ is the most stable one.

7 pages, 4 figures