Picosecond relaxation of X-ray excited GaAs

0508745 - ÚFP 2020 RIV GB eng J - Článek v odborném periodiku
Tkachenko, V. - Medvedev, Nikita - Lipp, V. - Ziaja, B.
Picosecond relaxation of X-ray excited GaAs.
High energy density physics. Roč. 24, September (2017), s. 15-21. ISSN 1574-1818. E-ISSN 1878-0563
Institucionální podpora: RVO:61389021
Klíčová slova: electron-lattice thermalization * band-structure * femtosecond * kinetics
Obor OECD: Optics (including laser optics and quantum optics)
Impakt faktor: 1.696, rok: 2017
Způsob publikování: Omezený přístup
https://www.sciencedirect.com/science/article/abs/pii/S1574181817300605?via%3Dihub

In this paper we present the current status of our theoretical studies on ultrafast relaxation of X-ray/XUV excited gallium arsenide. First, we discuss our previous approach, the unified model based on rate equations, two-temperature model and the extended Drude approach. By fitting the model to the available experimental data, we obtained realistic estimates on transient electronic temperature and electron-lattice thermalization timescale. Next, we make a step towards a rigorous description of the relaxation process with our hybrid code, XTANT. We extend the XTANT to include the band-specific effect of the suppression of collisional processes in GaAs, and perform dedicated simulations. We find that the extended model correctly describes the predicted transient non-isothermality of conduction and valence bands, however, currently, it cannot reproduce the experimentally observed reflectivity overshooting at 5-10 ps. The reason for this discrepancy is that the electron-phonon coupling rate implemented in XTANT, although successfully applied for diamond and silicon, clearly underestimates the strength of this coupling in GaAs. The outline for a respective model improvement is discussed.
Trvalý link: http://hdl.handle.net/11104/0299572