Abstract: GaN surface is clear etched by combination of KrF excimer laser irradiation and post chemical wet treatment using hydrochloric acid. KrF excimer laser irradiation ablates GaN surface and turns the ablated surface to Ga-rich layer. The Ga-rich layer is etched off by the hydrochloric acid treatment. X-ray photoelectron spectroscopy analysis reveals that the chemically etched surface has similar composition and chemical bonding to untreated GaN. The average roughness amazingly decreases to approximately 48 percent compared to the untreated GaN samples at the laser fluence increases beyond 1.5 J/cm$+2$/. !12
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