The basic principle of LED epitaxial‑wafer growth: gaseous precursors are delivered in a controlled manner onto a substrate wafer (mainly Sapphire and GaAs) heated to an appropriate temperature, so that a specific single‑crystal thin‑film can be grown on its surface. At present, Metal‑Organic Chemical Vapor Deposition (MOCVD) is the dominant technology for LED epitaxial‑wafer growth. Substrate materials for LED epitaxial wafers are the cornerstone of technological development in the semiconductor‑lighting industry. Different substrate materials require corresponding epitaxy‑growth processes, chip‑processing technologies and device‑packaging technologies. Substrate materials determine the technical roadmap for semiconductor lighting.