| CPC C30B 25/04 (2013.01) [C30B 25/20 (2013.01); C30B 29/406 (2013.01); H10D 62/405 (2025.01); H10D 62/8503 (2025.01)] | 5 Claims |

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1. A nitride semiconductor substrate, having a diameter of 2 inches or more and including a main surface,
wherein at a center of the main surface, an off-angle formed by a <0001> axis with respect to a normal of the center of the main surface is greater than 0° and 1° or less, and when an X-ray rocking curve of (0002) plane diffraction is measured by irradiating the main surface with Cu Kα1 X-rays via a two-crystal monochromator of a Ge (220) plane and a slit,
FWHMb is 38.5 arcsec or less,
difference FWHMa-FWHMb obtained by subtracting FWHMb from FWHMa is 30% or less of FWHMa, and
FWHMa≥FWHMb,
wherein FWHMa is full width at half maximum of the (0002) plane diffraction when a slit width in ω direction is 1 mm,
FWHMb is full width at half maximum of the (0002) plane diffraction when a slit width in the ω direction is 0.1 mm, and
the ω direction is a circumferential direction around a central axis that passes through a center of the nitride semiconductor substrate, is parallel to the main surface of the nitride semiconductor substrate, and is perpendicular to a direction in which the X-rays are incident on the center of the nitride semiconductor substrate, in the X-ray rocking curve measurement.
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