1. Field of the Invention
The present invention relates to a group III nitride semiconductor substrate production method, and a group III nitride semiconductor substrate. In particular, it relates to a group III nitride semiconductor substrate production method, which involves cutting a bulk crystal, and a group III nitride semiconductor substrate.
2. Description of the Related Art
Conventionally, a GaN substrate production method is known that includes vapor-growing a GaN single crystal on a substrate to produce a GaN monocrystalline ingot, and slicing the formed GaN monocrystalline ingot parallel to the growing direction to produce a GaN substrate.
According to the above production method, it is possible to obtain a GaN substrate with low dislocation density surface because dislocations extend in the GaN single crystal growing direction and are parallel to the substrate surface sliced by slicing the ingot parallel to the dislocation-extending direction.
Refer to JP-A-2007-84435, for example.
However, with the above GaN substrate production method, the problems may arise that when, to shorten the period of time of slicing, the slicing speed is increased, the crystal defect depth (the damaged layer depth) caused by slicing may be increased, and even after grinding the sliced surface, the surface roughness may be varied by saw marks formed in the sliced surface exposed by slicing parallel to the wire moving direction of a wire saw used in slicing.