Method for producing GaN layered substrate

A method for producing a GaN layered substrate, comprising the steps of:

• subjecting a C-plane sapphire substrate having an off-angle of 0.5 to 5 degrees to a high-temperature nitriding treatment at 800° C. to 1,000° C. and/or a treatment for deposition of crystalline AlN on the C-plane sapphire substrate to carry out a surface treatment of the C-plane sapphire substrate;
• carrying out epitaxial growth of GaN on the surface of the surface-treated C-plane sapphire substrate, so that a GaN film is formed on the surface of the surface-treated C-plane sapphire substrate, whereby a GaN film carrier having a surface of an N polar face is produced;
• forming an ion implantation region by carrying out ion implantation on the GaN film of the GaN film carrier;
• laminating and bonding a support substrate with a surface of the GaN film of the GaN film carrier, to which the ion implantation has been carried out;
• and
• performing delamination at the ion-implanted region in the GaN film to transfer a GaN thin film onto the support substrate, to obtain a GaN layered substrate having, on the support substrate, the GaN thin film whose surface is a Ga polar face.