Abstract: A Group III nitride semiconductor device has a semiconductor region, a metal electrode, and a transition layer. The semiconductor region has a surface comprised of a Group III nitride crystal. The semiconductor region is doped with a p-type dopant. The surface is one of a semipolar surface and a nonpolar surface. The metal electrode is provided on the surface. The transition layer is formed between the Group III nitride crystal of the semiconductor region and the metal electrode. The transition layer is made by interdiffusion of a metal of the metal electrode and a Group III nitride of the semiconductor region.

Abstract: A soldering device for radiator tanks comprises a large number of burner nozzles disposed along the entire width of and directed to the soldering area. Cooling pipes are provided on burner tables which can be adjusted so that the radiator can be inserted inside the gap formed therebetween. A control means shifts the times for starting and shutting off the supplying of an oxygen-containing gas from the burner ignition and fire extinction times.