Cooling and radiative recombination of resonantly excited 2D carriers in magnetic fields up to 25 T studied using picosecond time-resolved photoluminescence

The time-evolution of the photoluminescence from a GaAs/GaAlAs multi quantum well structure is studied using picosecond time-resolved spectroscopy in magnetic fields up to 25 T and under almost resonant excitation. Ultra short rise-times of 10-30 ps are found, while the observed decay consists of a fast component of 20-60 ps due to stimulated emission, and a slow component due to spontaneous emission of about 200 ps. From the magnetic field dependence of both the rise- and decay-time it is found that the carrier cooling rate due to phonon emission decreases with increasing magnetic field. © 1989.