Magnesium aluminate (MgAl2O4) can be used as the substrate substrate of III-V nitride device thin film, and is also widely used in acoustic wave and microwave devices and fast IC epitaxial substrates. In addition, it has a good lattice matching with epitaxial silicon thin layer. The self-doping of aluminum atoms in the epitaxial silicon thin layer is small, the thermal stability is good, and the expansion coefficient of silicon is relatively close, the hardness is small, the processing performance is better, etc., so it can be used as a high-quality insulating lining for ultra-high-speed large-scale integrated circuits One of the bottom materials. At present, we can provide twin-free, crystal-domain-free, and ultra-smooth high-quality substrate substrates with a maximum diameter of 2 inches (FWHM<50 arcsec, roughness Ra<0.5 nm).