Ambipolar diffusion of photoexcited carriers in bulk GaAs

摘要

The ambipolar diffusion of carriers in bulk GaAs is studied by using an ultrafast pump-probentechnique with a high spatial resolution. Carriers with a pointlike spatial profile are excited by antightly focused pump laser pulse. The spatiotemporal dynamics of the carriers are monitored by antime-delayed and spatially scanned probe pulse. Ambipolar diffusion coefficients are deduced fromnlinear fits to the expansion of the area of the profiles, and are found to decrease from aboutn170 cm2ns−1nat 10 K to about 20 cm2ns−1nat room temperature. Our results are consistent with thosendeduced from previously measured mobilities. © 2010 American Institute of Physics.nu0004doi:10.1063/1.3533664