Spin-Gratings and In-Well Carrier Transport Measurements in GaAs/AlGaAs Multiple Quantum Wells

We have recently demonstrated [1] that transient electron spin gratings created by cross-polarised excitation pulses at a wavelength resonant with the heavy hole exciton, can provide a new and unique way of measuring in-well electron drift mobilities in semiconductor multiple quantum well structures. This compares with the usual transient grating method in which only the ambipolar diffusion coefficient can be determined [2]. A comparison of concentration and spin grating decay rates allows the direct measurement of both the electron and hole drift mobilities in the same sample. In this work we extend these measurements to GaAs/AlGaAs multiple quantum wells with different well widths and compare results obtained under conditions of exciton saturation and broadening.