SELF-SUPPORTING GALLIUM NITRIDE CRYSTAL SUBSTRATE AND METHOD FOR MANUFACTURING SAME

摘要

Provided are a self-supporting gallium nitride crystal substrate that is characterized by having a dark spot density less than 2×108/cm2 and the surface thereof having a non-polar or semi-polar plane orientation, and a method for manufacturing the same. The method for manufacturing a self-supporting gallium nitride crystal substrate is characterized by comprising: using a sapphire base substrate wherein a plurality of grooves having a side wall, that is configured from, for example, the c-plane of sapphire single crystal and inclined to the principal surface of the base substrate, are formed; forming a gallium nitride crystal layer, said side wall being the origin of the lateral crystal growth; allowing the crystals to grow until the film thickness of the crystal layer attains at least 100 mum, preferably at least 300 mum; and then cooling the same to separate the gallium nitride crystal layer from the sapphire base substrate.