GaN epitaxial films on (0001)sapphire substrates were fabricated by laser ablation. An ArF excimer laser(193 nm, 25 ns) with an energy of 140 mJ/pulse was used for ablating cold-pressed GaN targets made from high-purity GaN powders. Just before the deposition, thermal cleaning of the substrate surface at 1073 K was essential. The substrate temperature was varied between 873 and 1073 K. Above 973 K, the epitaxial layers were obtained. When a buffer layer of GaN was deposited at lower temperatures before the epitaxial growth, the crystalline quality and surface morphology were greatly improved.