US Patent 7906791 Semiconductor light emitting element

Light extraction efficiency of a semiconductor light-emitting element is improved. A buffer layer, an n-type GaN layer, an InGaN emission layer, and a p-type GaN layer are laminated on a sapphire substrate in a semiconductor light-emitting element. A ZnO layer functioning as a transparent electrode is provided on the p-type GaN layer and concave portions are formed on a surface of the ZnO layer at two-dimensional periodic intervals. If a wavelength of light from the InGaN emission layer in the air is λ, an index of refraction of the ZnO layer at the wavelength λ is nzλ, and a total reflection angle at an interface between the ZnO layer and a medium in contact therewith is θz, a periodic interval Lz between adjacent concave portions is set in a range of λ/nzλ≦Lz≦λ/(nzλ×(1−sin θz)).