Chemical lift-off of (1122) semipolar GaN using periodic triangular cavities

Chemical lift-off of (1122) semipolar GaN using triangular cavities was investigated. The (1122) semipolar GaN was grown using epitaxial lateral overgrowth by metal-organic chemical vapor deposition on m-plane sapphire, in such a way as to keep N terminated surface of c-plane GaN exposed in the cavities. After regrowing 300 μm thick (1122) semipolar GaN by hydride vapor phase epitaxy for a free-standing (1122) semipolar GaN substrate, the triangular cavities of the templates were chemically etched in molten KOH. The (000-2) plane in the triangular cavities can be etched in the [0002] direction with the high lateral etching rate of 196 μm/min. The resulting free-standing (1122) semipolar GaN substrate was confirmed to be strain-free by the Raman analysis.