Temperature dependent carrier escape from quantum well states in GaAs/GaAlAs graded index laser structures

The steady-state equilibrium of photoexcited carrier population in quantum wells (QWs) in GaAs/GaAlAs graded index (GRIN) structures was studied by polarization dependent photocurrent analysis. The carrier escape energy was determined separately for polarized excitation parallel (TE) and perpendicular (TM) to the epitaxial sequence from an Arrhenius plot of the photocurrent magnitude. For that purpose either the spectrum was recorded for each temperature or the spectral feature related to the process of interest was tracked while the temperature was varied. Carrier escape of holes through the light hole band dominates the escape. Nonradiative pair recombination within the well and carrier escape by tunnelling are further loss processes.