III-nitride semiconductor laser device, and method of fabricating the III-nitride semiconductor laser device

A method of fabricating a III-nitride semiconductor laser device, comprising the steps of:

• preparing a substrate with a semipolar primary surface, the semipolar primary surface comprising a hexagonal III-nitride semiconductor;
• forming a substrate product having a laser structure, an anode electrode, and a cathode electrode, the laser structure comprising a substrate and a semiconductor region, and the semiconductor region being formed on the semipolar primary surface;
• after forming the substrate product, forming first and second end faces;
• and
• forming first and second dielectric multilayer films for an optical cavity of the nitride semiconductor laser device on the first and second end faces, respectively,
• the first and second end faces intersecting with a reference plane, the reference plane being defined by a normal axis to the semipolar primary surface and any one crystal axis of a- and m-axes of the hexagonal III-nitride semiconductor,
• the semiconductor region comprising a first cladding layer of a first conductivity type gallium nitride-based semiconductor, a second cladding layer of a second conductivity type gallium nitride-based semiconductor, and an active layer, and the active layer being provided between the first cladding layer and the second cladding layer,
• the first cladding layer, the second cladding layer, and the active layer being arranged in a direction of the normal axis,
• the active layer comprising a gallium nitride-based semiconductor layer,
• the semipolar primary surface of the substrate being inclined at an angle in a range of not less than 45 degrees and not more than 80 degrees and of not less than 100 degrees and not more than 135 degrees with respect to a plane perpendicular to a c+ axis vector, and the c+ axis vector indicating a direction of the <0001> axis of the nitride semiconductor,
• the c+ axis vector making an acute angle with a waveguide vector, and the waveguide vector indicating a direction from the second end face to the first end face, and
• a thickness of the second dielectric multilayer film being smaller than a thickness of the first dielectric multilayer film.