Characterization of GaN/SiC epilayers by picosecond four-wave mixing technique

This paper reports on the application of the picosecond four-wave mixing technique for the nondestructive characterization of the photoelectric properties of GaN layers grown on SiC substrates by hot-wall MOCVD. Grating kinetics at some periods and excitation intensities allowed determination of carrier lifetime of 60-80 ps, while the dependence of the diffraction efficiency vs. excitation intensity exhibited a threshold of fast radiative recombination at 2mJ/cm(2). The photoelectric properties of the GaN layer grown on SiC substrate are compared to those of a GaN layer of the same thickness grown on sapphire. A lower threshold value of recombination is attributed to the last sample.