Chemical lift‐off of GaN epitaxial films grown on c‐sapphire substrates with CrN buffer layers

GaN epitaxial films are grown on c-plane sapphire substrates with CrN buffer. The GaN layers show high crystalline quality and smooth surface morphology without being cracked. Selective etching of CrN buffer is performed by wet etching using conventional Cr metal etchant, which results in success ful lift-off of GaN thick layers. We confirm that the crystalline quality of GaN does not change through the etching process. These results indicate that the chemical lift-off process using CrN buffer is promising for production of both freestanding GaN substrates and vertical-structure devices. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)