A method and apparatus for growing low defect, optically transparent, colorless, crack-free, substantially flat,
single crystal Group III
nitride epitaxial
layers with a thickness of at least 10 microns is provided. These
layers can be grown on large area substrates comprised of Si, SiC,
sapphire, GaN, AlN, GaAs, AlGaN and others. In one aspect, the crack-free Group III
nitride layers are grown using a modified HVPE technique. If desired, the shape and the stress of Group III
nitride layers can be controlled, thus allowing concave, convex and flat layers to be controllably grown. After the growth of the Group III nitride layer is complete, the substrate can be removed and the freestanding Group III nitride layer used as a seed for the growth of a
boule of Group III nitride material. The
boule can be sliced into individual wafers for use in the fabrication of a variety of
semiconductor structures (e.g., HEMTs, LEDs, etc.).