Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator Bi2Se3
We report a transport study of exfoliated few monolayer crystals of topological insulator Bi2Se3 in an electric field effect geometry. By doping the bulk crystals with Ca, we are able to fabricate devices with sufficiently low bulk carrier density to change the sign of the Hall density with the gate voltage Vg. We find that the temperature T and magnetic field dependent transport properties in the vicinity of this Vg can be explained by a bulk channel with activation gap of approximately 50 meV and a relatively high-mobility metallic channel that dominates at low T. The conductance (approximately 2x7e2/h), weak antilocalization, and metallic resistance-temperature profile of the latter lead us to identify it with the protected surface state. The relative smallness of the observed gap implies limitations for electric field effect topological insulator devices at room temperature.
J. G. Checkelsky et al., "Bulk Band Gap and Surface State Conduction Observed in Voltage-Tuned Crystals of the Topological Insulator Bi2Se3," Physical Review Letters, vol. 106, no. 19, American Physical Society (APS), May 2011.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevLett.106.196801
Keywords and Phrases
Bulk Carrier; Bulk Crystals; Gate Voltages; High Mobility; Monolayer Crystals; Room Temperature; Surface State; Weak Antilocalization; Crystals; Electric Insulators; Magnetic Fields; Monolayers; Transport Properties; Electric Field Effects
International Standard Serial Number (ISSN)
Article - Journal
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