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

Islam, Saurav and Bhattacharyya, Semonti and Kandala, Abhinav and Richardella, Anthony and Samarth, Nitin and Ghosh, Arindam (2017) Bulk-impurity induced noise in large-area epitaxial thin films of topological insulators. In: APPLIED PHYSICS LETTERS, 111 (6).

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Abstract

We report a detailed study on low-frequency 1/f-noise in large-area molecular-beam epitaxy grown thin (similar to 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 x 10(17) cm(-2) eV(-1). In the presence of the 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 internal bulk defects are the dominant source of noise. Published by AIP Publishing.

Item Type:	Journal Article
Publication:	APPLIED PHYSICS LETTERS
Additional Information:	Copy right for this article belongs to the AMER INST PHYSICS, 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	09 Sep 2017 04:43
Last Modified:	09 Sep 2017 04:43
URI:	http://eprints.iisc.ac.in/id/eprint/57761

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