Sapphire Substrate For the production of LED chips, the choice of substrate material is the primary consideration.            Typically, epitaxial layers of GaN-based materials and devices are grown primarily on sapphire substrates. Sapphire substrate has many advantages: First, the sapphire substrate production technology is mature, the device quality is better; Secondly, sapphire stability is good, can be used in the high temperature growth process; Finally, sapphire mechanical strength is high, easy to handle And cleaning. Therefore, most of the processes are generally sapphire as a substrate.