DEEP-ULTRAVIOLET ENHANCED WET CHEMICAL ETCHING OF GALLIUM NITRIDE

We report a study of the ultraviolet (UV) irradiation effects on the w et chemical etching of unintentionally doped n-type gallium nitride (G aN) layers grown on sapphire substrates. When illuminated with a 253.7 nm mercury line source, etching of GaN is found to take place in aque ous phosphorus acid (H3PO4) and potassium hydroxide (KOH) solutions of pH values ranging from -1 to 2 and 11 to 15, respectively. Formation of I:allium oxide is observed on GaN when illuminated in dilute H3PO4 and KOH solutions. These results are attributed to a two-step reaction process upon which the UV irradiation is shown to enhance the oxidati ve dissolution of GaN. (C) 1998 American Institute of Physics.