Halogen Adsorption and Reaction with Bi₂(Se,Te)₃ and Bi/Bi₂(Se,Te)₃

Abstract

Bi2Se3 and Bi2Te3 and these same surfaces covered with Bi films are exposed to Br2 and Cl2 in ultrahigh vacuum. Low-energy electron diffraction and low-energy ion scattering are used to investigate the surface composition before and after halogen exposure. It is found that Br2 weakly chemisorbs to the Se- or Te-terminated clean surfaces and light annealing removes the adsorbates restoring the intact surfaces. In contrast, halogens dissociatively adsorb onto surfaces covered with an additional bilayer of Bi, showing a p-doping effect. Annealing these halogen-covered surfaces at 130°C causes Bi atoms to be chemically etched away and the surface reverts to a Se- or Te-termination. This work shows how halogen adsorption and reaction can be used to modify the surface termination of such materials.