Electronic structure and morphology of epitaxial Bi₂Te₂Se topological insulator films

Epitaxial films of the ternary topological insulator Bi₂Te₂Se were grown on Si(111) substrates and investigated for their surface electronic properties and morphology. We employ a Se-capping procedure allowing for the preparation of clean films in the surface-analysis experimental setups. Using angle-resolved photoelectron spectroscopy, we determine the dispersion of the topological surface state. With time after surface preparation, the spectroscopic features in the surface electronic structure exhibit significant temperature-dependent shifts to higher binding energies. Scanning tunneling microscopy images show terraces with typical step edge separations of 50 nm–150 nm. X-ray photoelectron spectroscopy indicates an increased Se concentration at the surface.