Surface Potential Dependence of the Topological Insulator Bi2se3 Studied by Scanning Photoemission and Kelvin Probe Microscopy

The atomic composition and electronic structure of topological insulators (TI) Bi2Se3 grown by the two-temperature Physical Vapor Deposition on n-type Si patterned substrates, have been followed in details during slight variation of the growth temperatures and values of thickness close to that of the topological transition (about 6nm), by means of submicron lateral probe photoemission with enhanced surface sensitivity (less than 1 nm). Raman and atomic force microscopy together with Kelvin probe microscopy cross-correlate the above results to provide a coherent picture where the signature of topology is clearly determined and distinguished from common insulators phases on the basis of the observed surface atomic composition.