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.

Probing the interplay between surface and bulk states in the topological Kondo insulatorSmB6through conductance fluctuation spectroscopy

“…At very high temperatures (regime IV, T > T K ), only the electrons in the dispersive 5d orbital contribute to electrical transport, and the entire current flows through the bulk of the sample. Unlike the case of topological insulators based on bismuth dichalcogenides [43], in SmB 6 we find that the noise in SSs and the bulk are uncorrelated; at ultralow temperatures the bulk has no discernible contribution to electrical transport, making SmB 6 ideal for probing the physics of topological surface states. Figure 10 shows a schematic of the setup used to measure low-frequency voltage noise.…”

Layered Topological Insulators and Semimetals for Magnetoresistance Type Sensors

“…In addition to the ratio of the MR and its anisotropy, another key factor that determines the device performance (accuracy and sensitivity) is the level of low‐frequency flicker noise (or the 1/ f noise) present in the device. 1/ f noise has been explored in TI systems . TRS protection can lead to noise reduction in TI surfaces.…”

“…TRS protection can lead to noise reduction in TI surfaces. Thus, at a small channel thickness, the noise magnitude of BSTS‐based TI devices can be extremely small, corresponding to a Hooge parameter of 10 −4 . However, quantitative experiments on MR accuracy or sensibility in sensor devices based on topological quantum materials are still lacking.…”

“…1/f noise has been explored in TI systems. [104][105][106][107] TRS protection can lead to noise reduction in TI surfaces. Thus, at a small channel thickness, the noise magnitude of BSTS-based TI devices can be extremely small, corresponding to a Hooge parameter of 10 −4 .…”

“…Thus, at a small channel thickness, the noise magnitude of BSTS-based TI devices can be extremely small, corresponding to a Hooge parameter of 10 −4 . [104] However, quantitative experiments on MR accuracy or sensibility in sensor devices based on topological quantum materials are still lacking. Quantum oscillations are superposed on the MR curve in the high magnetic field, [43,61,71] which is harmful to the MR accuracy.…”