Journal
ACS NANO
Volume 6, Issue 1, Pages 295-302Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn204239d
Keywords
topological insulator; aluminum passivation; thin films; Shubnikov-de Hass oscillations; weak antilocalization; surface state degradation
Categories
Funding
- Focus Center
- Center on Functional Engineered Nano Architectonics (FENA)
- Defense Advanced Research Projects Agency (DARPA)
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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 (AN) oscillations and weak antilocalization (WAL) effect, originated from the pi 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.
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