  We report on time-resolved and steady-state photoluminescence studies of
GaAs/AlGaAs V-groove quantum wire structures. Steady-state photoluminescence
experiments are performed in the temperature range from 8K to 200K. We evaluate
the relation between photoluminescence excitation and absorption and determine
experimentally an optical density in order to analyze the temperature
dependence of the photoluminescence spectra. We find that, at a temperature
above 60K, the photoexcited electron-hole pairs reach a thermal equilibrium at
the lattice temperature while, at a temperature below about 60K, they do not
reach a quasi-equilibrium in the steady-state. Time-resolved photoluminescence
studies performed at a carrier density of about 2. 104 cm-1 indicate that, at
60K, a quasi-equilibrium is reached on a time scale of 10 ps. Furthermore, the
hot carriers cool in about 100 ps to the lattice temperature. At 8K, however,
evidence of a non-thermal carrier distribution is found at the earliest times,
which suggests that carriers in extended states are not in thermal equilibrium
with carriers in localized states.
