Surface oxidation of the topological insulator Bi2Se3

Abstract

An understanding of the aging and oxidation of the (0001) surface of Bi2Se3 is critical to a comprehensive physical picture of its topologically protected surface states. Here, the authors contribute new experimental observations about the aging and oxidation process. The authors find that surface aging in ambient conditions occurs in two major steps. Within 2 h of exfoliation, a series of ∼3.2 Å high islands are observed by atomic force microscopy over approximately 10% of the surface. Subsequently, patch growth stops, and oxidation begins after the 2 h and continues until one quintuple layer has been oxidized. X-ray photoelectron spectroscopy shows no sign of oxidation before ∼120 min of exposure to air, and the oxygen 1 s peak, as well as oxidized Se 3d and Bi 4d peaks, are clearly present after ∼190 min of ambient exposure. Variable angle spectroscopic ellipsometry indicates that the oxidation of a full quintuple layer occurs on the time scale of days. These results are in good agreement with the time dependent changes observed in the surface crystal structure by second harmonic generation. In addition to providing the ability to nondestructively measure oxide on the surface of Bi2Se3 crystals, ellipsometry can be used to identify the thickness of Bi2Se3 flakes. With these methods, the authors have constructed a consistent, experimentally based model of aging process at the surface of Bi2Se3.

Thickness-dependent properties of ultrathin bismuth and antimony chalcogenide films formed by physical vapor deposition and their application in thermoelectric generators

“…2 d) were identified. The presence of oxidation-related peaks in the XPS spectra of ultrathin Bi 2 Se 3 and Sb 2 Te 3 films is related to the susceptibility of these materials to rapid oxidation in air [24,25], as the synthesized ultrathin films were stored under ambient conditions for several months.…”

Photosensing and Characterizing of the Pristine and In-, Sn-Doped Bi2Se3 Nanoplatelets Fabricated by Thermal V–S Process

“…Figure 4b presents the XPS spectra of Se 3d 5/2 and Se 3d 3/2 and the binding energies of 53.6 and 54.6 eV are associated with the Bi 2 Se 3 phase [45]. The peak at 58.9 eV is attributed to the SeO 2 phase [48,49]. The samples are stored in the ambient environment, causing the Bi 2 O 3 and SeO 2 phases to form on the surface of the nanoplatelets.…”

Interband transitions in semi-metals, semiconductors, and topological insulators: a new driving force for plasmonics and nanophotonics [Invited]

“…Such optical anisotropy can be found in other materials such as cuprates, ruthenates, magnesium diboride or graphite [100,101] and can be even suitable for achieving hyperbolic optical properties in specific spectral regions. However, in most of the works reporting the bulk dielectric function of p-block topological insulators [61,62,[102][103][104][105], anisotropy could not be properly resolved or was totally disregarded in the data analysis. Therefore, it is not clear yet whether the published data yield the in-plane dielectric function of the materials or a "pseudo" dielectric function mixing the in-plane and vertical dielectric function of the optically uniaxial material.…”