Abstract: The luminous efficiency of a nitride semiconductor device comprising a gallium nitride-based semiconductor layer formed on a dissimilar substrate is improved. An n-type layer formed on the substrate with a buffer layer interposed between them comprises a portion of recess-and-projection shape in section as viewed in the longitudinal direction. Active layers are formed on at least two side faces of the projection with the recess located between them. A p-type layer is formed within the recess. An insulating layer is formed on the top face of the projection, and on the bottom face of the recess. The n-type layer is provided with an n-electrode while the p-type layer is provided with a p-electrode contact layer. As viewed from the p-type layer formed within the recess in the gallium nitride-based semiconductor layer, the active layer and the n-type layer are located in an opposite relation to each other.

Abstract: A high external quantum efficiency is stably secured in a semiconductor light emitting device. At least one recess and/or protruding portion is created on the surface portion of a substrate for scattering or diffracting light generated in a light emitting region. The recess and/or protruding portion has a shape that prevents crystal defects from occurring in semiconductor layers.