We present a transmission electron microscope (TEM) and x-ray diffraction (XRD) study of metalorganic vapor phase epitaxy grown GaN layers on m-sapphire with Al(Ga)N interlayers. The interlayers are demonstrated to be beneficial in reducing the stacking fault (SF) density by more than 2.5 orders of magnitude from >2 × 106 cm−1 to <5 × 103 cm−1 as determined by TEM. XRD measurements along the GaN to the GaN reflection reveal a diffraction component originating in the basal plane SFs. Fitting the XRD signal enables a fast and simple determination of SF type and density which can even distinguish between the GaN buffer and the upper GaN layers and which is in reasonable agreement with TEM measurements.
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