Abstract: A semiconductor epitaxial substrate includes: a single crystal substrate; an AlN layer epitaxially grown on the single crystal substrate; and a nitride semiconductor layer epitaxially grown on the AlN layer, wherein an interface between the AlN layer and nitride semiconductor layer has a larger roughness than an interface between the single crystal substrate and AlN layer, and a skewness of the upper surface of the AlN layer is positive.

Abstract: A semiconductor epitaxial substrate includes: a single crystal substrate; an AlN layer epitaxially grown on the single crystal substrate; and a nitride semiconductor layer epitaxially grown on the AlN layer, wherein an interface between the AlN layer and nitride semiconductor layer has a larger roughness than an interface between the single crystal substrate and AlN layer, and a skewness of the upper surface of the AlN layer is positive.

Abstract: A semiconductor epitaxial substrate includes: a single crystal substrate; an AlN layer epitaxially grown on the single crystal substrate; and a nitride semiconductor layer epitaxially grown on the AlN layer, wherein an interface between the AlN layer and nitride semiconductor layer has a larger roughness than an interface between the single crystal substrate and AlN layer, and a skewness of the upper surface of the AlN layer is positive.

Abstract: A semiconductor epitaxial substrate includes: a single crystal substrate; an AlN layer epitaxially grown on the single crystal substrate; and a nitride semiconductor layer epitaxially grown on the AN layer, wherein an interface between the AlN layer and nitride semiconductor layer has a larger roughness than an interface between the single crystal substrate and AlN layer, and a skewness of the upper surface of the AlN layer is positive.

Abstract: The orientation of the rotating direction of an optical fiber in an optical fiber array takes the positional axial displacement into consideration. In a method of aligning the orientation of optical fibers, or the axial displacement in an optical fiber array having a plurality of optical fibers, and an optical fiber holding member, an enlarged image of the optical fiber is obtained for each of the optical fibers using an image pick-up means. Then, a distribution of the characterized image corresponding to the positions in the radial direction of the image of the optical fiber are obtained from the enlarged image. From the distribution of the characterized image, the orientation of the rotational direction to the center of the optical fiber, or the positional axial displacement of the core center, is measured.