ORCID Profile
0000-0002-4198-5892
Current Organisations
Academy of Scientific and Innovative Research
,
National Physical Laboratory CSIR
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Publisher: Wiley
Date: 03-12-2022
Abstract: The bulk carrier excitation influences the phonon dynamics, which can alter and modulate the surface charge density of topological insulators such as bismuth selenide (Bi 2 Se 3 ). This work investigates the charge carrier and phonon dynamics in Bi 2 Se 3 grown on various substrates. The orientation of the substrate, the size of the crystallites, and the misfit of the lattice affect the carrier and phonon dynamics. Bi 2 Se 3 thin films are grown under the same growth conditions on SiO 2 , Si(111), and SiN. Bi 2 Se 3 overlayers exhibit substrate‐dependent charge carrier relaxation channels and phonon dynamics. It is evident from Raman spectroscopy and ultrafast transient absorption spectroscopy that the heterointerface interactions of all three s les affect the vibration modes of Bi 2 Se 3 and coherent acoustic phonon oscillations in the NIR range. At 13.6, 41.2, and 34.4 GHz, the vibration modes of SiO 2 , Si(111), and SiN are equivalent. The propagation depth of phonon waves is shown by measuring the speed of sound in Bi 2 Se 3 overlayers on SiO 2 , Si(111), and SiN. This study demonstrates that the surface and bulk‐bound charge carriers of a topological insulator determine the frequency and velocity of the generated sound.
Publisher: AIP Publishing
Date: 02-2021
DOI: 10.1063/5.0038269
Abstract: We report the ultrafast carrier dynamics of an SnSe2–SnSe composite thin film (∼150 nm thick) deposited using thermal evaporation of in-house synthesized SnSe2 powder. Raman and UV–visible spectroscopy supports the optical properties (direct and indirect bandgaps of 1.86 eV and 0.96 eV, respectively). Ultrafast transient spectroscopy is used to study the charge excited state dynamics in the SnSe2–SnSe composite thin film in the femtosecond to nanosecond interval. An energy model has been proposed based on the ultrafast transient absorption and the thin film's steady-state absorption studies. This article provides comprehensive knowledge about the excited carriers and their relaxations in 0.9 ps–31.1 ns via different trap states.
Publisher: American Chemical Society (ACS)
Date: 02-07-2022
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 11-2023
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 02-2024
Publisher: Springer Science and Business Media LLC
Date: 29-09-2021
Publisher: Springer Science and Business Media LLC
Date: 04-04-2020
Publisher: Elsevier BV
Date: 10-2021
Publisher: Elsevier BV
Date: 04-2022
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 08-2022
Publisher: Springer Science and Business Media LLC
Date: 11-04-2021
No related grants have been discovered for Mahesh Kumar.