Electron-hole plasma dynamics in CdTe in the picosecond regime

The relaxation of photogenerated electron-hole plasmas is investigated in CdTe using time-resolved luminescence in the picosecond regime. The plasma temperature, the plasma density, and the band-gap renormalization are traced during the relaxation following the excitation pulse. Transient luminescence spectra are analyzed, first in a mostly used free-particle model and second, including carrier collision broadening calculated in the plasmon-pole approximation. The transient temperatures obtained with the second presumably correct model prove to be significantly lower. The plasma cooling is slowed down with increasing initial plasma density. The temperature decay is compared to plasma cooling theory including hot-phonon effects. The agreement is satisfactory for the densities ranging from 5×${10}^{16}$ ${\mathrm{cm}}^{\mathrm{-}3}$ to 4×${10}^{17}$ ${\mathrm{cm}}^{\mathrm{-}3}$. Additionally, good agreement is found between our experimental results of band-gap shrinkage and theory. This work represents the first simultaneous test of several aspects of the electron-hole plasma theory including the many-body line-shape theory, the quasiparticle damping, the band-gap renormalization, and the plasma cooling kinetics.