Congratulations to Hadar for getting out our first TI paper for the group!
Surface State Transport and Ambipolar Electric Field Effect in Bi2Se3 Nanodevices
Hadar Steinberg, Dillon R. Gardner, Young S. Lee & Pablo Jarillo-Herrero
Nano Letters ASAP (2010)
Electronic transport experiments involving the topologically protected states found at the surface of Bi2Se3 and other topological insulators require ﬁne control over carrier density, which is challenging with existing bulk-dopedmaterial. Here we report on electronic transport measurements on thin (<100 nm) Bi2Se3 devices and show that the density of the surface states can be modulated via the electric ﬁeld effect by using a top-gate with a high-k dielectric insulator. The conductance dependence on geometry, gate voltage, and temperature all indicate that transport is governed by parallel surface and bulk contributions. Moreover, the conductance dependence on top-gate voltage is ambipolar, consistent with tuning between electrons and hole carriers at the surface.