COMPOSITE SUBSTRATE, METHOD FOR MANUFACTURING SAME, METHOD FOR MANUFACTURING FUNCTIONAL LAYER FORMED OF GROUP 13 ELEMENT NITRIDE, AND FUNCTIONAL ELEMENT

摘要

A composite substrate (10) is provided with: a sapphire substrate (1A); a seed crystal film (4), which is provided on the surface of the sapphire substrate, and which is formed of gallium nitride crystal; and a gallium nitride crystal layer (7), which is crystal-grown on the seed crystal film (4), and which has a thickness of 200 mum or less. Voids (3) are provided at the interface between the sapphire substrate (1A) and the seed crystal film (4), and the ratio of the voids is 4.5-12.5 %.