Chemical lift-off of GaN epitaxial filmscurrent grown on c-sapphire substrates with CrN buffer layers

摘要

GaN epitaxial films are grown on c-plane sapphire substrates with CrN buffer. The GaN layers show high crystalline qual-ity 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.