Femtosecond studies of intraband relaxation in GaAs, AlGaAs, and GaAs/AlGaAs multiple quantum well structures

Abstract
Femtosecond intraband relaxation dynamics of hot carriers in highly excited states of GaAs, AlGaAs, and AlGaAs/GaAs multiple quantum well (MQW) structures are studied at room temperature using the equal-pulse correlation technique. Initial carrier lifetimes of 35, 60, and 50 fs are measured for GaAs, Al0.32Ga0.68As, and MQW structures for excitation with 2.02-eV photons at low carrier densities, and are in reasonable agreement with calculated scattering rates. The carrier-density dependence of these lifetimes is measured for densities in the range 1.5×1017–5×1019 cm−3.