Method for making free-standing GaN wafer, Wafer produced thereby, and associated methods and devices using the wafer

A method for making a free-standing, single crystal, gallium nitride (GaN) wafer includes forming a single crystal GaN layer directly on a single crystal LiAlO2 substrate using a gallium halide reactant gas, and removing the single crystal LiAlO2 substrate from the single crystal GaN layer to make the free-standing, single crystal GaN wafer. Forming the single crystal GaN layer may comprise depositing GaN by vapor phase epitaxy (VPE) using the gallium halide reactant gas and a nitrogen-containing reactant gas. Because gallium halide is used as a reactant gas rather than a metal organic reactant such as trimethygallium (TMG), the growth of the GaN layer can be performed using VPE which provides commercially acceptable rapid growth rates. In addition, the GaN layer is also devoid of carbon throughout. Because the GaN layer produced is high quality single crystal, it may have a defect density of less than about 10 cm.