OPTICAL PHONON COHERENCE AND POPULATION DECAYS IN III-V SEMICONDUCTORS

Investigations of optical phonon coherence and population decays in bu lk III-V semiconductors are discussed. The results are compared to our lifetime determinations using a non phonon-mode selective technique b ased on precise measurement of electron-lattice thermalization dynamic s. The measured LO phonon lifetimes were found to be consistent with t he dephasing times measured in intrinsic samples. In the presence of c arriers (for the density range 10(16)-10(17) cm(-3)), due to LO phonon -plasmon hybridization, the dephasing time is strongly reduced and bec omes much smaller than the lifetime which is almost not altered. The r oles of pure dephasing and population decay mechanisms in optical phon on relaxation are discussed for various carrier environment.