This page shows why silicon carbide is the optimal material for producing LEDs. Silicon carbide provides the closest lattice match to gallium nitride. This 1 to 0.967 match is shown in the graphic on the left and is much closer than the 1 to 1.148 match of sapphire that is shown in the middle graphic. In other words, silicon carbide has a 4.5 times better lattice match than sapphire to gallium nitride. The right image illustrates where this mismatch manifests itself. These mismatches create areas where the LED is less efficient resulting in ultimately fewer lumens per watt.