Topological surface states of Bi2Se3 with the coexistence of Se   vacancies
  Although topological surface states are known to be robust against non-magnetic surface perturbations, their band dispersions and spatial distributions are still sensitive to the surface defects. Take Bi2Se3 as an example, we demonstrated that Se vacancies modifies the surface band structures considerably. When large numbers of Se vacancies exist on the surface, topological surface states may sink down from the first to second quintuple layer and get separated from the vacancies. We simulated STM images to distinguish the surfaces with Se- and Bi-terminations. 
Binghai Yan, Delin Zhang, Claudia Felser
cond-mat.mtrl-sci