We present a systematic study of the exciton and electron-hole plasma photoluminescence dynamics in bulk GaAs for various lattice temperatures and excitation densities. The competition between the exciton and electron-hole pair recombination dominates the onset of the luminescence. We show that the metal-to-insulator transition, induced by temperature and/or excitation density, can be directly monitored by the carrier dynamics and the time-resolved spectral characteristics of the light emission. The dependence on carrier density of the photoluminescence rise time is strongly modified around a lattice temperature of 49 K, corresponding to the exciton binding energy (4.2 meV). In a similar way, the rise-time dependence on lattice temperature undergoes a relatively abrupt change at an excitation density of $120\text{–}180\times {10}^{15}{\mathrm{cm}}^{-3}$, which is about five times greater than the calculated Mott density in GaAs taking into account many body corrections.

• Received 26 July 2005

DOI:https://doi.org/10.1103/PhysRevB.73.035205