Abstract: In order to improve light-emission efficiency without degrading protection performance of a light-emitting layer structure a three p-type layer structure composed of first to third layers is provided in contact with a light-emitting layer structure. The first layer is an n-type AlGaN layer that serves as a protective layer, the third layer is a GaN:Mg layer that serves as a contact layer and the second layer is an AlGaN:Mg layer formed between these layers as an intermediate layer. The provision of the intermediate layer enables an InGaN layer to be thoroughly protected from heat during growth of layers above even if the n-type AlGaN layer is made thin, whereby the GaN:Mg layer can be brought near the light-emitting layer structure to enhance the efficiency of hole injection into the light-emitting layer structure and thus increase the light-emission efficiency.

Abstract: A diamond pn junction diode includes a p-type diamond thin-film layer formed on a substrate and an n-type diamond thin-film layer formed by forming a high-quality undoped diamond thin-film layer on the p-type diamond thin-film layer and ion-implanting an impurity into the high-quality undoped diamond thin-film layer, or alternatively includes an n-type diamond thin-film layer formed on a substrate and a p-type diamond thin-film layer formed by forming a high-quality undoped diamond thin-film layer on the n-type diamond thin-film layer and ion-implanting an impurity into the high-quality undoped diamond thin-film layer.

Abstract: A diamond semiconductor includes a high-quality thin diamond film layer with few crystal defects and few impurities, implanted with ions of dopant elements and controllable in conductivity determined by a kind and a concentration of the dopant elements. The diamond semiconductor is fabricated by a method including the step of implanting ions of dopant elements into a high-quality thin diamond film layer with few crystal defects and few impurities under conditions that can attain given distribution of concentrations of the dopant elements and with the high-quality thin diamond film layer kept to a temperature in accordance with the conditions so as not to be graphitized, to thereby enable the diamond semiconductor to have conductivity determined by a kind and a concentration of the dopant elements.