Patent ID: 8822247

Claim:
A manufacturing method of an optical semiconductor element including a semiconductor film having a crystal structure of a hexagonal system, said manufacturing method including: forming a plurality of recesses arranged at equal intervals along a crystal axis of said semiconductor film in a surface of said semiconductor film; and performing an etching process on the surface of said semiconductor film, to form a plurality of protrusions arranged according to an arrangement form of said plurality of recesses and deriving from the crystal structure of said semiconductor film in the surface of said semiconductor film; wherein: said plurality of recesses are arranged, with other recesses adjacent to any one recess being respectively placed at vertexes of a regular hexagon, such that two opposite sides of said regular hexagon are parallel to a [1-100] direction or [11-20] direction of a crystal axis of said semiconductor film; said etching process comprises a wet etching process using a tetramethylammonium hydroxide solution, such that an etching speed in said recesses is lower as compared with an etching speed of a C-plane, and such that etching of the C-plane, the etching speed of which is relatively higher, starts preferentially first and progresses thereby exposing a predetermined crystal plane and forming, as the protrusions, multiple six-sided pyramid-shaped micro-cones with a formed point of each recess as an apex; said plurality of protrusions are formed such that said plurality of protrusions have a closest packed arrangement; and the surface of said semiconductor film is the C-plane, and a plurality of crystal planes are exposed in inside walls of each of said plurality of recesses.