Optical studies of carrier transport in layered structures and crystals of wide bandgap semiconductors

Role of threading dislocations and carrier localization effect have been studied in GaN/sapphire, InGaN/GaN heterostructures, and free-standing GaN layers by using time-resolved picosecond four-wave mixing technique. Diffusion and nonlinear recombination in nitrides as well as in heavily doped bulk SiC or homoepilayers have been investigated at various excitation densities and wavelengths to demonstrate advantages of nonlinear optical techniques for characterization of photoelectric properties of semiconductors.