Group-iii nitride semiconductor laser device, and method for fabricating group-iii nitride semiconductor laser device

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

• preparing a substrate of a hexagonal group-III nitride semiconductor, the substrate having a semipolar primary surface;
• forming a substrate product having a laser structure, an anode electrode and a cathode electrode, the laser structure including the substrate and a semiconductor region, and the semiconductor region being formed on the semipolar primary surface, and;
• scribing a first surface of the substrate product in part in a direction of the a-axis of the hexagonal group-III nitride semiconductor;
• and
• carrying out breakup of the substrate product by press against a second surface of the substrate product, to form another substrate product and a laser bar,
• the first surface being opposite to the second surface,
• the semiconductor region being located between the first surface and the substrate,
• the laser bar having first and second end faces, the first and second end faces being formed by the breakup, and the first and second end faces extending from the first surface to the second surface,
• the first and second end faces constituting a laser cavity of the group-III nitride semiconductor laser device,
• the anode electrode and the cathode electrode being formed on the laser structure,
• 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, 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 along a normal axis to the semipolar primary surface,
• the active layer comprising a gallium nitride-based semiconductor layer,
• a c-axis of the hexagonal group-III nitride semiconductor of the substrate tilting at an angle ALPHA with respect to the normal axis toward the m-axis of the hexagonal group-III nitride semiconductor,
• the angle ALPHA falling within a range of not less than 45° and not more than 80° or within a range of not less than 100° and not more than 135°, and
• the first and second end faces intersecting with an m-n plane defined by the normal axis and the m-axis of the hexagonal group-III nitride semiconductor.