Native point defects in Bi2Se3: A first-principles study.

The naturally grown Bi 2 Se 3 is always n -type doped by native point defects, although the p -type Bi 2 Se 3 is much desirable as a promising thermoelectric material and topological insulator. We use first-principles calculations to identify the origin of the n -type tendency in bulk Bi 2 Se 3 : The Se vacancies (V S e 1 and V S e 2) and Se B i antisite dominate the donorlike doping with low formation energy, while the predisposed Bi S e 1 defect results in the pair of V S e 1 and Bi interstitial, which is also a donor rather than an acceptor. For Bi 2 Se 3 (111) surface, by calculating the defect formation energy and surface charge density distribution, we find that the band structures modulated by the defects explicitly account for the existing experimental observations of n -type preference. Moreover, the topological surface states can be significantly affected by the n -type tendency of Bi 2 Se 3. • The Se vacancies and Se Bi antisite dominate the donorlike doping of Bi 2 Se 3. • The electronic structures of the native point defects are discussed in detail. • Surface charge density distributions of defected Bi 2 Se 3 (111) are presented. • Defects have dramatic influence on the surface states of Bi 2 Se 3. [ABSTRACT FROM AUTHOR]