Ultrafast carrier dynamics and optical nonlinearities of low-temperature-grown InGaAs/InAlAs multiple quantum wells

Low-temperature-grown Be-doped In0.53Ga0.47As/In0.52Al0.48As multiple quantum wells are investigated via wavelength-dependent time-resolved nonlinear absorption measurements. Annealed Be-doped material, in contrast to annealed undoped material, is found to retain the carrier lifetime reduction induced by low-temperature growth in this narrow-gap material system. This is attributed to Be–As complexes which, in addition to producing high resistivity material, provide anneal–stable trap states. We also report that ultrafast band-edge and photoinduced absorption effects can produce subpicosecond absorption recovery in material exhibiting much longer (20 ps) defect-meditated carrier trapping.