title: Bulk-Induced 1/f Noise at the Surface of Three-Dimensional Topological Insulators.
abstract: Slow intrinsic fluctuations of resistance, also known as the flicker noise or 1/f-noise, in the surface transport of strong topological insulators (TIs) is a poorly understood phenomenon. Here, we have systematically explored the 1/f-noise in field-effect transistors (FET) of mechanically exfoliated Bi1.6Sb0.4Te2Se TI films when transport occurs predominantly via the surface states. We find that the slow kinetics of the charge disorder within the bulk of the TI induces mobility fluctuations at the surface, providing a new source of intrinsic 1/f-noise that is unique to bulk TI systems. At small channel thickness, the noise magnitude can be extremely small, corresponding to the phenomenological Hooge parameter γH as low as ≈10(-4), but it increases rapidly when channel thickness exceeds ∼1 μm. From the temperature (T)-dependence of noise, which displayed sharp peaks at characteristic values of T, we identified generation-recombination processes from interband transitions within the TI bulk as the dominant source of the mobility fluctuations in surface transport. Our experiment not only establishes an intrinsic microscopic origin of noise in TI surface channels, but also reveals a unique spectroscopic information on the impurity bands that can be useful in bulk TI systems in general.
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Semonti
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Mitali
authors.initials: M
authors.lastname: Banerjee
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Hariharan
authors.initials: H
authors.lastname: Nhalil
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Saurav
authors.initials: S
authors.lastname: Islam
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Chandan
authors.initials: C
authors.lastname: Dasgupta
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Suja
authors.initials: S
authors.lastname: Elizabeth
authors.affiliation: Department of Physics, Indian Institute of Science , Bangalore 560 012, India.
authors.forename: Arindam
authors.initials: A
authors.lastname: Ghosh
keywords: 1/f noise; Topological Insulator; generation-recombination noise