In situ spectroscopy of intrinsic Bi₂Te₃ topological insulator thin films and impact of extrinsic defects

Combined in situ x-ray photoemission spectroscopy, scanning tunneling spectroscopy, and angle resolved photoemission spectroscopy of molecular beam epitaxy grown Bi₂Te₃ on lattice mismatched substrates reveal high quality stoichiometric thin films with topological surface states without a contribution from the bulk bands at the Fermi energy. The absence of bulk states at the Fermi energy is achieved without counterdoping. We observe that the surface morphology and electronic band structure of Bi₂Te₃ are not affected by in vacuo storage and exposure to oxygen, whereas major changes are observed when exposed to ambient conditions. These films help define a pathway towards intrinsic topological devices.