Carrier transport in asymmetrically confined 1.55 mu m multiple quantum well laser structures

Asymmetrically confined multiple quantum well laser structures have recently been very successful in reaching high modulation bandwidths up to 26 GHz, reported in the IncaAs/InGaAlAs material system. We have measured the effective carrier transport time in structures of this kind by performing parasitic-free optical modulation experiments. The result is one specific transport time for each confinement layer width. We show that down to layer widths of about 100 nm this effective time for both types of carriers is given by a pure diffusion process for InGaAs/InGaAlAs. Finally, a diffusion constant for the barrier/confinement carriers results in InGaAlAs material which is in very good agreement with reported mobilities. (C) 1996 American Institute of Physics.