Erlangen 2018 – scientific programme
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A: Fachverband Atomphysik
A 2: Attosecond Science I (joint session A/MO)
A 2.3: Talk
Monday, March 5, 2018, 11:30–11:45, K 1.011
Valley-resolved Electronic Coherences in Silicon Observed by Attosecond Transient Absorption Spectroscopy — •Michael Zürch1, Peter M. Kraus1, Hung-Tzu Chang1, Scott K. Cushing1, Daniel M. Neumark1,2, and Stephen R. Leone1,2,3 — 1Department of Chemistry, University of California, Berkeley, CA 94720, USA — 2Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA — 3Department of Physics, University of California, Berkeley, CA 94720, USA
Understanding the absorption of light and subsequent carrier dynamics in semiconductors plays a crucial role for optimizing next-generation photonic devices for increasingly faster performance. Here, attosecond transient absorption spectroscopy is employed for studying electronic coherences in single crystalline silicon during excitation by an intense 5-fs optical pulse. Transient absorption changes in the conduction band (CB) of silicon are monitored by an attosecond pulse at the silicon L-edge. In a frequency-over-energy Fourier analysis of the recorded transient absorption in comparison to the band structure coherences are identified. The data suggests that the optical pulse can coherently couple the valence band (VB) and CB at various critical points of the band structure. The time domain measurement allows measuring lifetimes of these coherences as well as their sequence of generation. The results provide insight into complex couplings between bands that take place during excitation with broadband ultrashort laser pulses, an effect that should be general for most semiconductor materials.