III-N Heteroepitaxial Devices on Rock Salt Substrates

Described herein are rock salt substrates and methods of making thereof that are useful as epitaxial substrates for semiconducting materials, including ultra-wide bandgap materials. Advantageously, the described rock salt substrates may be useful as substrates for Group III (Al, Ga, In)-N substrate allowing for pseudomorphic growth of novel, desirable materials. The rock salt may be provided as a bulk material or deposited as a thin film. These substrates may allow for generation of high Al content semiconductor devices with ultra-wide bandgap and other useful properties.