Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: Ultrafast electron dynamics at surface and interfaces II
O 38.2: Vortrag
Dienstag, 10. März 2026, 10:45–11:00, TRE/MATH
Investigating the light-induced metallization of ZnO through time-resolved photoemission spectroscopy — Gian Marco Pierantozzi1, Federico Motti1, Matteo Gatti2, •Monika Schied1, Alice Crosato3, Thomas Sartori3, Riccardo Cucini1, Giorgio Rossi1,4, Fausto Sirotti2, and Giancarlo Panaccione1 — 1CNR – Istituto Officina dei Materiali (IOM), Trieste, Italy — 2École polytechnique, Paris, France — 3Università Ca’ Foscari Venezia, Italy — 4Università degli Studi di Milano, Italy
With a direct bandgap of ∼3.4 eV and a high exciton binding energy (∼60 meV), ZnO is ideal for optoelectronics and excitonic studies. Under optical excitation, the system shows ultrafast metallization with several relaxation timescales [1,2]. The relevance of defects in stabilizing the photoinduced metallic state is known, but many aspects of the processes remain unclear. Here we investigate the ultrafast dynamics of the optically populated conduction band and the Zn 3d core level with time- and angle-resolved photoemission spectroscopy after resonantly pumping, in order to disentangle the excitations of defect levels. Our experiments cover the whole metallization process in ZnO. We observe a fast rise in the conduction band population within 100 fs, a slower temperature-dependent rise, probably due to carrier transport and redistribution, a decay on the ns timescale and a long-lasting metastable state. All these dynamics occur also pumping below resonance, albeit to a lower extent, highlighting the role of the defect levels.
[1] L. Gierster et al. Nat. Comm. 12:978 (2021);
[2] L. Gierster et al., Far. Disc. 237, 58 (2022)
Keywords: Ultrafast carrier dynamics; Time-resolved photoemission; High-Harmonic Generation; Light-induced metallization