Bulk-impurity induced noise in large-area epitaxial thin films of topological insulators

Abstract

We report a detailed study on low-frequency 1/f-noise in large-area molecular-beam epitaxy grown thin (10 nm) films of topological insulators as a function of temperature, gate voltage, and magnetic field. When the Fermi energy is within the bulk valence band, the temperature dependence reveals a clear signature of generation-recombination noise in the defect states in the bulk band gap. However, when the Fermi energy is tuned to the bulk band gap, the gate voltage dependence of noise shows that the resistance fluctuations in surface transport are caused by correlated mobility-number density fluctuations due to the activated defect states present in the bulk of the topological insulator crystal with a density of D${}_{it}=3.2\times 10^{17}$ cm${}^2$eV${}^{-1}$. In the presence of a magnetic field, noise in these materials follows a parabolic dependence, which is qualitatively similar to mobility and charge-density fluctuation noise in non-degenerately doped trivial semiconductors. Our studies reveal that even in thin films of (Bi,Sb)${}_2$Te${}_3$ with thickness as low as 10 nm, the intrinsic bulk defects are the dominant source of noise.

arXiv comment15 pages, 4 figures

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Cited by in corpus (4)

• Low temperature saturation of phase coherence length in topological insulators
• Universal conductance fluctuations and direct observation of crossover of symmetry classes in topological insulators
• Electrically Tunable Wafer-Sized Three-Dimensional Topological Insulator Thin Films Grown by Magnetron Sputtering
• Signature of pseudo-diffusive transport in mesoscopic topological insulators