ANGLE-RESOLVED PHOTOEMISSION AND FIRST-PRINCIPLES STUDIES OF TOPOLOGICAL THIN FILMS BY

Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have protected conducting states on their edge or surface. The exotic electronic properties of topological materials are of great interest for spin-related electronics and quantum computation. In this thesis research, the combination of angle-resolved photoemission spectroscopy (ARPES) and first principles calculation is used to examine the electronic properties of topological thin films and 2D electronic systems with large spin-orbit splitting. The topological thin films are prepared in situ by molecular beam epitaxy (MBE) method and characterized by experimental tools such as reflection high-energy electron diffraction (RHEED) and low energy electron diffraction (LEED). The systems investigated in this thesis include topological Sb, Bi2Te3, Be2Se3 thin films, Bi films, and Bi/Ag surface alloy. Topological Sb films have been successfully fabricated on Si(111) substrates. By examining the connection pattern between surface states and the quantum well bulk states, our photoemission spectra show clearly the topological order of the Sb films. Whe