Affords GaN crystal substrates that can reduce the occurring of cracks and fractures in the GaN crystal substrates when the semiconductor devices are manufactured, semiconductor devices including them, methods of manufacturing the semiconductor devices, and methods of identifying the GaN crystal substrates. A gallium nitride crystal substrate has a surface area of 10 cm2 or more. The difference between the maximum and the minimum of Raman shifts corresponding to the E2H phonon mode in a region except for a region from the outer periphery in the surface of the gallium nitride crystal substrate to a line 5 mm radially inward from the outer periphery of the surface is 0.5 cm−1 or less. And also affords semiconductor devices including them, methods of manufacturing the semiconductor devices, and methods of identifying the GaN crystal substrates.