HOT-CARRIER DYNAMICS IN A (GAINSB INAS)/GAINALASSB SUPERLATTICE MULTIPLE-QUANTUM-WELL MEASURED WITH MID-WAVE INFRARED, SUBPICOSECOND PHOTOLUMINESCENCE UP-CONVERSION/

We have extended the technique of subpicosecond photoluminescence upco nversion to the mid-wave infrared spectral region and have used this s ystem to investigate the energy relaxation of hot, optically injected electron-hole pairs in a narrow-band-gap (2.32 mu m) (GaInSb/InAs)/GaI nAlAsSb superlattice multiple quantum well. These and similar structur es are currently of interest as the active region for mid-wave infrare d diode lasers. The measurements demonstrate that carriers, which are injected with nearly 1 eV of excess energy, are well described by a ho t, thermalized distribution in the wells within 2 ps after excitation. For a carrier density of 10(17) cm(-3), cooling by optical phonon emi ssion is essentially complete 15 ps after injection. By fitting the ti me dependence of the carrier temperature, we estimate an effective car rier-optical-phonon scattering time of 1.2 ps. (C) 1997 American Insti tute of Physics.