Provided are a III-group nitride single-crystal ingot reduced in a cracking percentage at a long-growing time, a III-group nitride single-crystal substrate manufactured by using the ingot, a method for manufacturing the III-group nitride single-crystal ingot, and a method for manufacturing the III-group nitride single-crystal substrate. The manufacturing method is characterized by comprising a step of etching the side face of a backing substrate, and a step of epitaxially-growing a III-group nitride single-crystal of a hexagonal system having crystal faces on the side faces, over a backing substrate. For reducing the cracking at the long growing time of the ingot, it is necessary to suppress the deposition of a polycrystal or a different-plane orientation crystal on the periphery of the single crystal. By etching off the processing-degenerated layer in advance from the side face of the backing substrate, as described above, a crystal plane is formed on the side face of the III-group nitride single-crystal ingot formed on the backing substrate, so that the deposition of the polycrystal or the different-plane orientation crystal is suppressed to reduce the cracking.
展开▼
