Coherent folded longitudinal acoustic phonons in a GaAs/AlAs long-period superlattice have been investigated by using a reflection-type two-color pump-probe technique under the condition that the wave vector of the probe pulse in the sample exceeds the mini-Brillouin zone. The coherent oscillations observed in the time-domain signals indicate the propagation of the phonon wave packet through th...

A set of hydrodynamic equations modeling strong ionization in semiconductors is formally derived from a kinetic framework. To that purpose, a system of Boltzmann transport equations governing the distribution functions of conduction electrons and holes is considered. The charge carriers obey a degenerate gas statistics and their kinetic energy relations are arbitrary. The umklapp collisions are...

The optimum thickness of a silicon solar cell base is determined using phenomelogic parameters, which are the minority carriers diffusion coefficient and recombination velocity at back side, influenced by Lorentzs law Umklapp process.The results obtained consistent with generation charge deep in monochromatic light long wavelength.

In this paper we review our work on thermal and thermoelectric properties of semiconductor low-dimensional structures, e.g. quantum wells and quantum wires, with emphasis on the effects of spatial confinement of acoustic phonons. We particularly concentrate on calculation of the phonon relaxation rates in mass-difference, Umklapp, point defect, and dislocation scattering processes that takes in...

The pressure dependence of the Mott, spin-density-wave and superconducting instabilities of the metallic state of the Bechgaard and Fabre salts is analyzed using weak coupling scaling theory. We show how the mechanism of quantum interference between pairings in the density-wave and superconducting channels, when combined to the influence of intrachain Umklapp scattering and inter-chain hopping ...