| Autor: |
Biswas, Sangram, Gopal, R. K., Singh, Sourabh, Kant, Raushan, Mitra, Chiranjib, Bid, Aveek |
| Předmět: |
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| Zdroj: |
Applied Physics Letters; 9/23/2019, Vol. 115 Issue 13, pN.PAG-N.PAG, 5p, 6 Graphs |
| Abstrakt: |
Despite several years of studies, the origin of slow-kinetics of charge-carriers at the surface-states of strong topological insulators remains abstruse. In this article, we report on studies of charge dynamics of thin films of the 3-dimensional strong topological insulator material BiSbTeSe1.6 grown by pulsed laser deposition (PLD). The bulk of the films was insulating, making them suitable for transport studies of topological surface-states. Despite being disordered and granular, the films show definite signatures of the presence of topological surface-states with electronic transport coherence lengths comparable to those of high-quality grown films grown by molecular beam epitaxy (MBE). At high temperatures, the resistance fluctuations in these films were found to be dominated by trapping-detrapping of charge carriers from multiple defect-levels of the bulk. At low temperatures, fluctuations in the resistance of surface-states, arising due to the coupling of surface transport with defect dynamics in bulk, determine the noise. We thus confirm that the measured low-frequency fluctuations in these films, over the entire temperature range of 20 mK–300 K, are determined primarily by bulk defect density. The magnitude of noise was comparable to that measured on bulk-exfoliated films but was slightly higher than that in MBE grown films. Our studies establish PLD as a viable route to develop high-quality topological insulator materials. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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