Studying ultrafast carrier dynamics in GaAs and GaAs/AlGaAs devices with few-cycle pump-probe reflectometry*

Over the last decade, advances in novel materials such as two-dimensional (2D) materials, metamaterials, plasmonics, and negative-electron-affinity (NEA) structures have triggered rapid growth in the development of ultrafast optoelectronic devices. This calls for simple yet effective approaches to characterize ultrafast dynamics in these materials and devices. Few-cycle pump-probe reflectometry (PPR) offers both high temporal resolution and broad spectral coverage in a simple configuration. In this talk, I will present our latest work on the study of transient carrier dynamics in bulk GaAs and photoelectron transportation/relaxation in GaAs/AlGaAs NEA photocathodes using few-cycle PPR. In addition to experimental results, theoretical models on photoelectron transportation in layered structures are also discussed, and theory-experiment comparisons are presented.