title: Observation of coherent phonon-plasma coupled modes in wide gap semiconductors by transmission pump-probe measurements.
abstract: We have investigated coherent LO phonon properties in zinc-based II-VI widegap semiconductors, focusing on phonon-plasma coupled modes. By a careful treatment of the time evolution of the signals in ZnS, ZnSe, and ZnTe, we found a frequency upshift as the pump intensity increases. Using a classical coupled oscillator model, we have explained the pump intensity dependence of both the shift and the decay rates by a mixing of highly damped two-photon generated plasma. From the linear dependence between them we can estimate the photo-excited carrier mobilities, leading to a new powerful estimation method to measure the mobility.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Kunugita
authors.forename: Kanji
authors.initials: K
authors.lastname: Hatashita
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ohkubo
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ema