Ultrafast physics in semiconductor microstructures

Analyzed is picosecond photoluminescence data obtained from quasi-two- and quasi-zero-dimensional electron systems in GaAs/AlGaAs multiple quantum wells and CdSSe/glass spherical quantum wells. Important results are: (1) nonequilibrium phonons produced in the energy relaxation process of quasi-two-dimensional carriers in a vicinity of phonon wave number q sub e could behave like coherent Bosons within a short time period. The effects of nonequilibrium phonons for photogenerated carriers in undoped GaAs quantum wells are to slow the energy relaxation and to shorten the recombination lifetime. (2) Electron-hole recombination dynamics in quasi-OD was interpreted based on the carrier confinement model. Ultrafast expansion of carriers in asymmetric GaAs quantum wells as observed under picosecond excitation. Dynamical changes in the band structure of GaAs and GaSe were measured under shock waves.