title: Revelation of topological surface states in Bi2Se3 thin films by in situ Al passivation.
abstract: Topological insulators (TIs) are extraordinary materials that possess massless, Dirac-like topological surface states in which backscattering is prohibited due to the strong spin-orbit coupling. However, there have been reports on degradation of topological surface states in ambient conditions, which presents a great challenge for probing the original topological surface states after TI materials are prepared. Here, we show that in situ Al passivation inside a molecular beam epitaxy (MBE) chamber could inhibit the degradation process and reveal the pristine topological surface states. Dual evidence from Shubnikov-de Hass (SdH) oscillations and weak antilocalization (WAL) effect, originated from the π Berry phase, suggests that the helically spin-polarized surface states are well preserved by the proposed in situ Al passivation. In contrast, we show the degradation of surface states for the unpassivated control samples, in which the 2D carrier density is increased 39.2% due to ambient n-doping, the SdH oscillations are completely absent, and a large deviation from WAL is observed.
authors.affiliation: Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, USA.
authors.forename: Murong
authors.initials: M
authors.lastname: Lang
authors.forename: Liang
authors.initials: L
authors.lastname: He
authors.forename: Faxian
authors.initials: F
authors.lastname: Xiu
authors.forename: Xinxin
authors.initials: X
authors.lastname: Yu
authors.forename: Jianshi
authors.initials: J
authors.lastname: Tang
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Xufeng
authors.initials: X
authors.lastname: Kou
authors.forename: Wanjun
authors.initials: W
authors.lastname: Jiang
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Fedorov
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D001729:Bismuth / Q000737:chemistry*; D004553:Electric Conductivity; D008422:Materials Testing; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012643:Selenium / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D000535:Aluminum; D012643:Selenium; D001729:Bismuth