  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.
