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Electrical properties and deep electron and hole traps spectra are compared for undoped n-GaN films grown by hydride vapor phase epitaxy (HVPE) in the regular process (standard HVPE samples) and in HVPE process optimized for decreasing the concentration of residual donor impurities (improved HVPE samples). It is shown that the residual donor density can be reduced by optimization from ∼1017 cm-3 to (2-5)×1014 cm-3. The density of deep hole traps and deep electron traps decreases with decreased donor density, so that the concentration of deep hole traps in the improved samples is reduced to ∼5×1013 cm-3 versus 2.9×1016 cm-3 in the standard samples, with a similar decrease in the electron traps concentration. [ABSTRACT FROM AUTHOR]

We report studies of the morphological, electrical, and optical properties of InN grown by hydride vapor phase epitaxy. The layers have been grown on c-plane sapphire substrates and epitaxial GaN, Al0.7Ga0.3N, and AlN templates grown on sapphire. InN properties are found to depend on template type with improvement of crystal structure in the template substrate order AlN→AlGaN→GaN. X-ray studies reveal InN layers grown on template substrates to be relaxed with lattice constants a=3.542 Å and c=5.716 Å. The Raman spectra and optical gaps of the InN layers, vary with free-carrier concentration in agreement with previous studies. We obtain a value of 2.5±0.2 for the index of refraction of InN. [ABSTRACT FROM AUTHOR]