Patent ID: 8432946

Claim:
A nitride semiconductor laser diode having a quantum well layer comprising: a mixed crystal of Al x1 In y1 Ga 1-x1-y1 N (x1≧0.5, y1≧0 and 1−x1−y1≦0.5) in a group III nitride semiconductor multilayer structure having a major growth surface defined by a nonpolar plane, with a cavity direction perpendicular to a c-axis in an opposing direction to a laser emitting end face and a reflective end face, light reciprocating between the laser emitting end face and the reflective end face and being amplified, wherein the group III nitride semiconductor multilayer structure includes a multiple quantum well structure obtained by alternately stacking the quantum well layer and a barrier layer made of Al x2 In y2 Ga 1-x2-y2 N (x2>x1, y2≧0 and 1−x2−y2<0.5) having a higher Al concentration than that of the quantum well layer, and the laser emitting end face and the reflective end face are provided at end faces of the quantum well layer with regard to a direction perpendicular to a thickness direction of the quantum well layer so that the cavity direction along which light is emitted is parallel to the quantum well layer, wherein planarity of the major growth surface in c-axis direction is within 10 Å.