Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 13: Poster I
HL 13.46: Poster
Montag, 18. März 2024, 15:00–18:00, Poster E
THz Spectroscopy on Bi2Se3 — •Debankit Priyadarshi1,2, Amit Haldar1, Sunil S. Kushvaha3, Manfred Fiebig2, and Shovon Pal1 — 1School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni, India. — 2Department of Materials, ETH Zurich, Zurich, Switzerland. — 3CSIR-National Physical Laboratory, New Delhi, India.
Topological insulators (TI) have come up as an important condensed matter system showing exotic metallic surface states protected by their topology and time reversal symmetry. The investigation of the conductivity of these surface states is difficult with traditional electrical techniques due to contributions from the free carriers in the bulk and the quantum well states to the total conduction. Terahertz (THz) spectroscopy is an emergent field in probing the conduction properties of these surface states due to the low photon energies (meV) of the THz radiation. Our measurements show contributions from Drude-like charge carriers and two Lorentz oscillator-like resonances to the conductivity of the Bi2Se3. The oscillator responses are attributed to the bulk-phonon resonance and inter-sub-band transitions in the quantum well states. The Drude response is expected to have contributions from the surface state carriers, 2D electron gas present on the quantum well states and free carrier states of the bulk. Going into the relaxation dynamics of these carriers by doing pump-probe measurements would reveal the exact contribution of the surface state carriers to the conductivity.
Keywords: Terahertz (THz) spectroscopy; Topological insulators; Surface states; Time-domain spectroscopy; Conductivity of semiconductors