title: Nanoclusters of CaSe in calcium-doped Bi2Se3 grown by molecular-beam epitaxy.
abstract: In calcium (Ca) doped Bi2Se3 films grown by molecular beam epitaxy, nanoclusters of CaSe are revealed by high-angle annular dark field imaging and energy dispersive x-ray spectroscopy analysis using a scanning transmission electron microscope. As the interface between the ordinary insulator CaSe and topological insulator, Bi2Se3, can host topological nontrivial interface state, this represents an interesting material system for further studies. We show by first principles total energy calculations that aggregation of Ca atoms in Bi2Se3 is driven by energy minimization and a preferential intercalation of Ca in the van der Waals gap between quintuple layers of Bi2Se3 induces reordering of atomic stacking and causes an increasing amount of stacking faults in film. The above findings also provide an explanation of less-than-expected electrical carrier (hole) concentrations in Ca-doped samples.
authors.affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China.
authors.forename: Panju
authors.initials: P
authors.lastname: Shang
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Bao
authors.initials: B
authors.lastname: Zhao
authors.forename: Xianqi
authors.initials: X
authors.lastname: Dai
authors.forename: Li
authors.initials: L
authors.lastname: Bin
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Jia
authors.forename: Quan
authors.initials: Q
authors.lastname: Li
authors.forename: Maohai
authors.initials: M
authors.lastname: Xie