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Screening ineffectiveness and THz emission at bare LO phonon frequencies

F. M. Souza·J. C. Egues
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Abstract

Within a hydrodynamic approach we investigate the dynamics of an inhomogeneous electron-hole gas coupled to phonons in Te and the corresponding THz emission. We find that the longitudinal inhomogeneity of the photogenerated electron-hole gas -- due to short absorption lengths in Te -- gives rise to screening ineffectiveness for non-zero wave-vector modes. This allows for THz dynamics and emission at the bare LO phonon frequency nu_{LO} even at high carrier densities. Screening ineffectiveness thus provides an appealingly simple explanation for the existence of bare modes at nu_{LO} in longitudinally inhomogeneous systems such as Te; no lateral inhomogeneity of the excitation spot is needed here.

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F. M. Souza, J. C. Egues. 2002-09-22. Screening ineffectiveness and THz emission at bare LO phonon frequencies. https://doi.org/10.1103/physrevb.66.060301

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