Doping effects of Sb and Pb in epitaxial topological insulator Bi 2 Se3 thin films: An in situ angle-resolved photoemission spectroscopy study

Abstract

Bi2 Se3 is a typical three-dimensional topological insulator but always exhibits metallic behavior due to heavy n-type doping. With in situ angle-resolved photoemission spectroscopy, we have systematically studied the doping effects of Sb and Pb on the electronic structure of Bi 2 Se3 films prepared by molecular beam epitaxy. The surface chemical potential of Bi2 Se3 can be tuned by 110 and 145 meV by doping Sb and Pb atoms, respectively. By codoping Pb and Sb, the Fermi level can be shifted from above to below the Dirac point. The underlying mechanism in different doping effects of Sb and Pb is discussed. © 2010 American Institute of Physics.