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We have investigated the polaron dynamics in n-doped InAs/GaAs self-assembled quantum dots by pump-probe midinfrared spectroscopy. A long T1 polaron decay time is measured at both low temperature and room temperature, with values around 70 and 37 ps, respectively. The decay time decreases for energies closer to the optical phonon energy. The relaxation is explained by the strong coupling for the electron-phonon interaction and by the finite lifetime of the optical phonons. We show that, even for a large detuning of 19 meV from the LO photon energy in GaAs, the carrier relaxation remains phonon assisted.

This Letter reports the first experimental observation of heavy and light excitons by resonant Brillouin scattering of polaritons in ZnSe. The number of the Brillouin peaks as well as their variations with the excitation light energy are well accounted for on the basis of a three-branch polariton dispersion curve in which the longitudinal-transverse splitting ${E}_{\mathrm{LT}}$ and the exchange energy $\ensuremath{\Delta}$ mix both kinds of excitons. The observation of the three branches allows us to determine ${E}_{\mathrm{LT}}$, $\ensuremath{\Delta}$, and the translational masses ${M}_{h}$ and ${M}_{1}$ of heavy and light excitons.

Etude des variations de la conductivite electrique en fonction de l'epaisseur des couches ultraminces metalliques