Substrate, epitaxial layer provided substrate, method for producing substrate, and method for producing epitaxial layer provided substrate
The present invention provides a substrate formed at a low cost and having a controlled plate shape, an epitaxial layer provided substrate obtained by forming an epitaxial layer on the substrate, and methods for producing them. The method for producing the substrate according to the present invention includes an ingot growing step serving as a step of preparing an ingot formed of gallium nitride (GaN); and a slicing step serving as a step of obtaining a substrate formed of gallium nitride, by slicing the ingot. In the slicing step, the substrate thus obtained by the slicing has a main surface with an arithmetic mean roughness Ra of not less than 0.05 μm and not more than 1 μm on a line of 10 mm.
1. A substrate formed of gallium nitride,
the substrate having a main surface with a surface roughness Ra of not less than 0.05 μm and not more than 1 μm on a line of 10 mm,
said main surface having a damaged layer formed thereon,
said damaged layer having a maximum depth of not more than 10 μm, said damaged layer having an average depth of not more than 5 μm;
wherein in said main surface thereof, a region constituting a Ga atomic plane and a region constituting a N atomic plane are disposed on the same flat plane.
2. The substrate according to claim 1 , having a shape warped to project at said main surface which is mainly constituted by a Ga atomic plane, and having the warpage with a height of more than 0 μm and not more than 50 μm.
3. The substrate according to claim 1 , used as a substrate for forming a light emitting device or an electronic circuit device.
4. The substrate according to claim 1 , wherein in said main surface, at least one of an arithmetic mean roughness Ra, a maximum height Rz, and a ten-point mean roughness Rzjis is measured in a direction perpendicular to a direction in said main surface in which a wire saw extends upon slicing using said wire saw is larger in value than a corresponding one measured in a direction along the direction in said main surface in which said wire saw extends.