Intrinsic surface dipole in topological insulators

Abstract

We calculate the local density of states of two prototypical topological insulators (Bi${}_2$Se${}_3$ and Bi${}_2$Te${}_2$Se) as a function of distance from the surface within density functional theory. We find that, in the absence of disorder or doping, there is a 2 nm thick surface dipole the origin of which is the occupation of the topological surface states above the Dirac point. As a consequence, the bottom of the conduction band is bent upward by about 75 meV near the surface, and there is a hump-like feature associated with the top of the valence band. We expect that band bending will occur in all pristine topological insulators as long as the Fermi level does not cross the Dirac point. Our results show that topological insulators are intrinsic Schottky barrier solar cells.

5 pages, 3 figures, sections rewritten to improve clarity, figure and refs added, results unchanged, published version

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Cited by in corpus (5)

• Band bending at the surface of Bi${}_2$Se${}_3$ studied from first principles
• Impact of ultrafast transport on the high-energy states of a photoexcited topological insulator
• Ionic and electronic properties of the topological insulator Bi${}_2$Te${}_2$Se investigated using $\beta$-detected nuclear magnetic relaxation and resonance of ${}^8$Li
• Coherent control of current injection in zigzag graphene nanoribbons
• Observability of superconductivity in Sr-doped Bi2Se3 at the surface using scanning tunneling microscope