| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high quality semiconductor crystal nearly free from dislocations. SOLUTION: When a substrate layer (a desired semiconductor crystal) of a group III nitride-based compound is grown on a ground substrate having a plurality of projection parts, cavities where no semiconductor crystal is deposited are formed at each of spaces between the projected parts, depending on the size of each projected part, the distance between the projected parts, crystal growth conditions, or the like. Therefore, when the thickness of the substrate layer is made sufficiently larger than the height of the projected parts, an internal stress or an external stress tends to act on the projected parts in a concentrated manner. These stresses act especially on the projected parts as the shear stress, and when the stresses become large enough, fracture occurs at the projected parts. Accordingly, it becomes possible to easily separate the ground substrate and the substrate layer by the use of these stresses and to obtain the semiconductor crystal independent from the ground substrate. The stresses are more easily concentrated on the projected parts as the sizes of the cavities become larger, and it becomes possible to separate the substrate layer from the ground substrate without failure. |
