The metrological capability of the picosecond four-wave mixing (FWM) technique for
evaluation of the photoelectrical properties of GaN heterostructures grown on sapphire,
silicon carbide, and silicon substrates as well as of free-standing GaN films is demonstrated.
Carrier recombination and transport features have been studied in a wide excitation,
temperature, and dislocation density (from∼ 1010 to 106cm− 2) range, exploring non-
resonant refractive index modulation by a free carrier plasma. The studies allowed to …