BASE, SUBSTRATE WITH GALLIUM NITRIDE CRYSTAL LAYER, AND PROCESS FOR PRODUCING SAME

摘要

Provided is a substrate having a GaN crystal layer, the substrate comprising a sapphire base and, deposited thereon, a layer of GaN crystals that have a low threading dislocation density and high crystallinity, wherein a surface having any of a variety of plane orientation has been formed. For example, the main surface of the GaN crystal layer in the substrate is constituted of the a-plane (<11-20> plane) or m-plane (<1-100> plane) or of the <11-22> plane. Also provided is a process for producing the substrate. The substrate having a gallium nitride crystal layer comprises a sapphire base and a gallium nitride crystal layer formed on the base by crystal growth, wherein the gallium nitride crystal layer has been formed, by lateral crystal growth, from the lateral walls of a plurality of grooves formed in the main surface of the sapphire base, the lateral walls being constituted, for example, of the c-plane, so as to form a surface which is parallel to the main surface, the surface being constituted of a nonpolar plane, e.g., the a-plane or the m-plane, or of a semi-polar plane, e.g., the 8 per cm2, preferably 1.85×108 per cm2 or less, especially preferably 1.4×108 per cm2 or less.