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HL: Fachverband Halbleiterphysik
HL 11: Ultra-fast Phenomena I
HL 11.2: Vortrag
Montag, 17. März 2025, 16:15–16:30, H14
Hot-Electron-Induced Substrate Response in Transient Absorption Spectroscopy of Tantalum — •Erik Willem de Vos1,2, Sergej Neb1, Marko Hollm1, Florence Burri1, Lukas Gallmann1, and Ursula Keller1 — 1Department of Physics, Institute for Quantum Electronics, ETH Zurich, Switzerland — 2Department of Materials, ETH Zurich, Zurich, Switzerland
We show that for extreme ultraviolet transient absorption spectroscopy measurements on thin-film metals, the substrate can significantly contribute to the observed change in absorption even if the substrate is transparent to the excitation wavelengths of the pump pulse and does by itself not produce a transient signal. Irradiation of a thin-film tantalum layer deposited on a silicon nitride substrate by a near-infrared femtosecond pulse is found to excite a coherent acoustic phonon in both the tantalum as well as the substrate. The response in the substrate rises on sub-picosecond timescales and is the result of direct excitation by the hot-electron distribution in the metal layer.
Keywords: Transient Absorption Spectroscopy; Charge Transport; Ultrafast; Transition Metals; Silicon Nitride