Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3

Bi2Se3 is a topological insulator with metallic surface states residing in a large bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping after exposure to atmosphere, thereby reducing the relative contribution of surface states in total conductivity. In this letter, transport measurements on Bi2Se3 nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi2Se3 under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological surface states. Appropriate surface passivation or encapsulation may be required to probe topological surface states of Bi2Se3 by transport measurements

Sonnenschutzverglasung

The glass has a transparent panel with lens structures (3) on the surface which faces the sun. The focal plane of the lens structures lies as far as possible behind the panel. A flat layer of a thermotropic material (5) is arranged behind the panel, so that the focal plane of the lens structures lies as much as possible in the layer. The lens structures may be spherical, three-dimensional lenses, or may be cylindrical or Fresnel lenses. The panel may also be separated from the layer by a cavity. ADVANTAGE - Does not have to be used only in south-facing orientations