Bulk gallium nitride, demanded as a substrate for high power lasers and other devices, typically reveals high dislocation density, incorporated stress and substantial lattice curvature due to involvement of non-native seeds applied in its production process. Resulting bow limits both enlargement of substrates diameter and yield in laser manufacturing. Within approaching limits of methods resulting in such quasi bulk material, increase of interest in truly bulk material is observed.

In this work results of structural characterization of high quality ammonothermal GaN are presented. Besides expected low dislocation density (being of the order of 10³ cm^-2) the most interesting feature seems perfect flatness of the crystal lattice of studied crystals. Regardless the size of crystals, lattice curvature radius exceeds 100 m, whereas better crystals reveal radius of several hundred meters and the best above 1000 m. Excellent crystallinity manifests in very narrow X-ray diffraction peaks of FWHM values about 17 arc sec.

High quality and homogeneity of ammonothermal GaN crystals proves that hopes put in such truly bulk material are justified and that it can be a breakthrough in mass implementation of high-power GaN-based devices.

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1. Preparation of free-standing GaN substrates from thick GaN layers crystallized by Hydride Vapor Phase Epitaxy on ammonothermally grown GaN seeds
2. Ammonothermal growth of GaN substrates
3. Podłoża AMMONO-GaN przyszłością elektroniki półprzewodnikowej