| 摘要 |
PROBLEM TO BE SOLVED: To provide a group III nitride semiconductor substrate for laser diodes (LD's) in which a flat cleavage plane having little irregularity such as uneven levels can be obtained, and a group III nitride semiconductor epitaxial substrate for LD's using the same.SOLUTION: A group III nitride semiconductor substrate 6 for LD's has a diameter of not less than 25 mm and a thickness of not less than 250 μm. In an outer periphery within 5 mm from the outer edge of the group III nitride semiconductor substrate 6 for LD's, at least a portion at the outer edge side exhibits a tensile stress as a stress within the main surface of the group III nitride semiconductor substrate 6 for LD's, and the tensile stress is relatively larger than a stress in a portion nearer to the central side than the portion at the outer edge side of the group III nitride semiconductor substrate 6 for LD's. |
