Fe-doped semi-insulating GaN substrates prepared by hydride vapor-phase epitaxy using GaAs starting substrates

An Fe-doped thick GaN layer was grown by hydride vapor-phase epitaxy on a (1 1 1)A GaAs starting substrate. By removing the GaAs substrate, a 400-μm-thick (0 0 0 1) GaN substrate having a smooth surface and an Fe concentration of 1.5×1019 cm−3 was obtained. X-ray diffraction rocking curves of the (0 0 0 2) and (1 0 1¯ 0) planes of the GaN substrate had narrow full-widths at half-maximum of 410 and 360 arcsec, respectively. The etch-pit density of the GaN substrate was 8×106 cm−2. Extended X-ray absorption fine structure analysis revealed that the Fe atoms are substituting for the Ga in the GaN. The GaN substrate had a high resistivity of 8.8×1012 Ω cm at room temperature.