Nitride semiconductor laser device and method of manufacturing the nitride semiconductor laser device

A nitride semiconductor laser device comprising:

• a nitride semiconductor substrate having a first main surface and a second main surface located on opposite sides of said nitride semiconductor substrate;
• a nitride semiconductor layer disposed on said first main surface of said nitride semiconductor substrate;
• a ridge-shaped stripe disposed on said nitride semiconductor layer, said ridgeshaped stripe having a longitudinal axis;
• and
• a resonance surface forming an optical waveguide in a direction perpendicular to, the longitudinal axis of said ridge-shaped stripe;
• wherein both said first main surface and said second main surface of said nitride semiconductor substrate comprise 1) a first region having a first crystal growth surface in a first crystal growth plane, and 2) a second region having a second crystal growth surface at least different from that of the first region, and at least one of said first main surface and said second main surface of said nitride semiconductor substrate includes a recessed area disposed in the second region;
• wherein the first region of said first main surface is located substantially beneath the first region of said second main surface, and the second region of said first main surface is located substantially above the second region of said second main surface;
• and
• wherein the first region on both said first main surface and said second main surface of said nitride semiconductor substrate has fewer dislocations than that in the second region on both said first main surface and said second main surface of said nitride semiconductor substrate.