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.