Growth, morphology and stability of Au in contact with the Bi2Se3(0 0 0 1) surface

We report a combined microscopy and spectroscopy study of Au deposited on the Bi₂Se₃(0001) single crystal surface. At room temperature Au forms islands, according to the Volmer–Weber growth mode. Upon annealing to 100 °C the Au deposits are not stable and assemble into larger and thicker islands. The topological surface state of Bi₂Se₃ is weakly affected by the presence of Au. Contrary to other metals, such as Ag or Cr, a strong chemical instability at the Au/Bi₂Se₃ interface is ruled out. Core level analysis highlights Bi diffusion toward the surface of Au islands, in agreement with previous findings, while chemical interaction between Au and atomic Se is limited at the interfacial region. For the investigated range of Au coverages, the Au/Bi₂Se₃ heterostructure is inert towards CO and CO₂ exposure at low pressure (10⁻⁸ mbar) regime.