Development of 50 mm diameter non-polar gallium nitride substrates for device applications

We report the development of large 50 mm diameter free standing wafers of GaN. GaN layers up to 350 /spl mu/m thick have been grown by HVPE on lattice-matched LiAlO/sub 2/ substrates. The original oxide substrates were removed by wet chemical etching, and the defect structure of the GaN wafers has been investigated. The issue of stacking faults vs. polar inversion domains has been resolved in favor of ABABACAC stacking sequences. A UV-emitting LED (368 nm) has been developed on these substrates, using molecular beam epitaxy.