Interplay between the hot phonon effect and intervalley scattering on the cooling rate of hot carriers in GaAs and InP

The influence of hot phonon effect and intervalley scattering on the hot carrier cooling rate was investigated using femtosecond time-resolved photoluminescence spectroscopy in bulk GaAs and InP, two electronically similar but vibrationally distinct semiconductors. In both materials, a broad photoluminescence signal that extends from the band gap energy to values larger than the pump pulse energy was observed during the first few picoseconds after photoexcitation, for different excitation energies (1.7, 1.88, and 2.4?eV) at high carrier densities (>1019?cm-3). Different hot carrier relaxation times were observed in GaAs and InP for different excitation energies, demonstrating the influence of intervalley scattering phenomena in GaAs. When electrons were not energetic enough to access satellite valleys, longer decay transients were observed for InP compared with GaAs. This provides experimental evidence of the hot phonon effect in InP. Temperature transients were calculated by analyzing the topography of the two-dimensional spectra. Copyright (c) 2011 John Wiley & Sons, Ltd.