Plasmon-phonon-assisted electron-hole recombination in Si at very high carrier density

As the electron-hole density in Si, and the corresponding plasma frequency, increase to equal or exceed the indirect energy gap, a new recombination channel opens up. We calculate the rate of such a recombination process to first order in the phonon coupling and the emission of a single plasmon. We find that at such high densities (of the order of ${10}^{21}$/${\mathrm{cm}}^3$) this channel strongly inhibits further increase of the carrier density even a picosecond after the pump-laser pulse.