Abstract: In a light-emitting diode, which comprises epitaxial wafer where a gallium phosphide or a gallium phosphide arsenide mixed crystal epitaxial layer is grown on a III-V family compound single crystal substrate having zinc blende type crystal structure, the surface of said substrate has a plane tilted by 5 to 16.degree. from a (100) plane toward ?010!, ?001!, ?0-10! or ?00-1!, or a plane having crystallographically equivalent crystal plane orientation to this plane. As a result, it is possible to improve light emitting output and to ensure longer service life.