KrF excimer laser induced ablation–planarization of GaN surface

The surface roughness of an as-grown GaN epilayer is reduced using a combination of KrF excimer laser irradiation and post chemical wet treatment. KrF excimer laser irradiation ablates GaN surfaces, resulting in the formation of a Ga-rich layer on the surface. The Ga-rich layer is etched off by hydrochloric acid treatment. X-ray photoelectron spectroscopic XPS. analysis reveals that the chemically etched surface has similar composition and chemical bonding to those of untreated GaN. The average roughness Ra.is improved by ;43% compared with an untreated GaN sample with a laser fluence of over 2.0 Jrcm2. q1999 Elsevier Science B.V. All rights reserved