Vapour Phase Growth of Thick Monocrystalline GaN Epitaxial Layers by Sandwich-Method

摘要

The characterization of the GaN epilayers from 70 to 250 micrometers thicknessgrown by SSM on the 6H-SiC substrates was performed. Free carrier concentration in initially undoped GaN samples was found to range between 2 and 6 x 10(exp 17)/cu cm. Rocking curve measurements of the GaN layers grown by SSM reveal the full width of half maximum (FWHM) from 150 to 400 arc.sec. Three-dimensional 15-20 arc.sec. disoriented wirtzite domains looked like the hexagonal prism in size of cells of 50 nm were found. Correlation between the spectral luminescence characteristics, its spatial inhomogeneity and structural perfection of the grown layers was shown. Increasing of wide-band emission in visual spectrum and it spatial inhomogeneity was suggested to be caused by the local stoichiometry deviation. The Fe, Ni, Mn impurities states in the GaN crystals were discovered and identified by the EPR method.