Surface Structure of In Situ Cleaved Single Crystal Bi2Se3 Measured by   Low Energy Ion Scattering
  Bismuth Selenide is a two-dimensional topological insulator material composed of stacked quintuple layers (QL). The layers are held together by a weak van der Waals force that enables surface preparation by cleaving. Low energy ion scattering experiments (LEIS) show that Bi2Se3 cleaved under ultra-high vacuum (UHV) has a Se-terminated structure that is consistent with cleaving between QLs. Comparison of experimental data to molecular dynamics simulations confirms the Se-termination and provides an estimate of the surface relaxation. 
Weimin Zhou, Haoshan Zhu, Jory A. Yarmoff
cond-mat.mtrl-sci