The electrical properties, deep level spectra, optical transmission, and luminescence spectra were measured on freestanding GaN crystals grown by hydride vapor phase epitaxy. The samples are semi-insulating n type with room temperature resistivity of 3.8 X 10(9) Omega cm and high. electron mobility of 715 cm(2)/V s. The Fermi level in these samples is pinned by a Fe-related level near E-c-0.57 eV that could be due to the Fe2+/Fe3+, transition. This level manifests itself also as a strong blue luminescence band peaked near 2.85 eV. An additional Fe-related band with optical threshold near 1.6 eV is observed in optical transmission spectra. The samples are paramagnetic, suggesting an absence of significant Fe precipitation. (c) 2007 American Vacuum Society.