Preparation of 3 inch freestanding GaN substrates by hydride vapor phase epitaxy with void‐assisted separation

By using the hydride vapor phase epitaxy and a void‐assisted separation method, freestanding 3 inch GaN substrates were successfully fabricated for the first time, and the process showed an excellent reproducibility. A thick GaN layer 3.2 inches in diameter was easily separated from the base substrate. No cracks were generated during the separation process, and the separation process was no more difficult than that of 2 inch GaN substrates. The dislocation density was of the order of 106 cm–2. The carrier density was approximately 1 × 1018 cm–3 and the mobility was 3.4 × 102 cm2 V–1 s–1. The concentrations of impurities, estimated by secondary‐ion mass spectrometry, were below the limit of detection, except for Si. The Si concentration was approximately 1 × 1018 cm–3, which is in good agreement with the carrier density. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)