  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.
