Electron-ion coupling in semiconductors beyond Fermi's golden rule

Abstract

In the present work, a theoretical study of electron-phonon (electron-ion) coupling rates in semiconductors driven out of equilibrium is performed. Transient change of optical coefficients reflects the band gap shrinkage in covalently bonded materials, and thus, the heating of atomic lattice. Utilizing this dependence, we test various models of electron-ion coupling. The simulation technique is based on tight-binding molecular dynamics. Our simulations with the dedicated hybrid approach (XTANT) indicate that the widely used Fermi's golden rule can break down describing material excitation on femtosecond time scales. In contrast, dynamical coupling proposed in this work yields a reasonably good agreement of simulation results with available experimental data.

References in corpus (4)

• Electron-phonon coupling and energy flow in a simple metal beyond the two-temperature approximation
• Thermal and nonthermal melting of silicon under femtosecond x-ray irradiation
• Observation of inhibited electron-ion coupling in strongly heated graphite
• Time-resolved observation of band-gap shrinking and electron-lattice thermalization within X-ray excited gallium arsenide

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