Chemical planarization of GaN using hydroxyl radicals generated on a catalyst plate in H2O2 solution

A novel technique for planarizing gallium nitride (GaN) wafers has been developed. In this method, hydroxyl radicals (OH) catalytically generated on a polishing plate are used to oxidize the surface of a GaN wafer, and the produced oxide is dissolved in the solution. H2O2 is employed as the source of OH. Iron is used as the catalyst material that functions as the polishing plate. A GaN wafer was placed on the iron plate in the H2O2 solution, and it was rotated relative to the plate with a controlled contacting load. Extremely flat surfaces that were free from scratches or pits were obtained for the Ga-polar GaN surface. Atomic force microscope images of the processed surface indicate that it is well ordered and that it has an atomic step-terrace structure.