title: Negligible surface reactivity of topological insulators Bi2Se3 and Bi2Te3 towards oxygen and water.
abstract: The long-term stability of functional properties of topological insulator materials is crucial for the operation of future topological insulator based devices. Water and oxygen have been reported to be the main sources of surface deterioration by chemical reactions. In the present work, we investigate the behavior of the topological surface states on Bi2X3 (X = Se, Te) by valence-band and core level photoemission in a wide range of water and oxygen pressures both in situ (from 10(-8) to 0.1 mbar) and ex situ (at 1 bar). We find that no chemical reactions occur in pure oxygen and in pure water. Water itself does not chemically react with both Bi2Se3 and Bi2Te3 surfaces and only leads to slight p-doping. In dry air, the oxidation of the Bi2Te3 surface occurs on the time scale of months, in the case of Bi2Se3 surface of cleaved crystal, not even on the time scale of years. The presence of water, however, promotes the oxidation in air, and we suggest the underlying reactions supported by density functional calculations. All in all, the surface reactivity is found to be negligible, which allows expanding the acceptable ranges of conditions for preparation, handling and operation of future Bi2X3-based devices.
authors.affiliation: Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia. yashina@inorg.chem.msu.ru
authors.forename: Lada V
authors.initials: LV
authors.lastname: Yashina
authors.forename: Jaime
authors.initials: J
authors.lastname: Sánchez-Barriga
authors.forename: Markus R
authors.initials: MR
authors.lastname: Scholz
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Volykhov
authors.forename: Anna P
authors.initials: AP
authors.lastname: Sirotina
authors.forename: Vera S
authors.initials: VS
authors.lastname: Neudachina
authors.forename: Marina E
authors.initials: ME
authors.lastname: Tamm
authors.forename: Andrei
authors.initials: A
authors.lastname: Varykhalov
authors.forename: Dmitry
authors.initials: D
authors.lastname: Marchenko
authors.forename: Gunther
authors.initials: G
authors.lastname: Springholz
authors.forename: Günther
authors.initials: G
authors.lastname: Bauer
authors.forename: Axel
authors.initials: A
authors.lastname: Knop-Gericke
authors.forename: Oliver
authors.initials: O
authors.lastname: Rader