PHOTOINDUCED INTERSUBBAND ABSORPTION IN BARRIER DOPED MULTI-QUANTUM-WELLS

The intersubband absorption and its photomodulation by above barrier-gap excitation in a barrier n-doped GaAs/AlGaAs multiple quantum well structure are reported. The e1-e2 intersubband transition is observed as an absorption band centered at 149 meV and polarized along the growth axis. The photoinduced absorption measured at temperatures below 150K consists of two parts: a bleaching band at the low energy side of the e1-e2 absorption band, and an absorption band on its high energy side. The photoinduced bleaching below 149 meV is assigned to a reduction in the e1 electron population due to recombination with excess holes resulting from electrons captured by the barrier donors. The photoinduced absorption above 149 meV is probably due to the e1:hh1-e2:hh1 exciton absorption. © 1990.