GaN LEDs on Si Substrate

Fabrication of GaN LEDs on Si is an attractive work but also with great challenge. One needs to overcome the huge difference in lattice parameter and thermal expansion coefficient between GaN and Si. With the help of substrate patterning and AlN/AlGaN buffer layer technologies, stress can be well controlled and high-quality crack-free GaN with low dislocation density are successfully grown. By strain engineering and utilizing V-defect in the active region, high-efficiency LED structure is developed. The chip fabrication process of LED on Si substrate is totally different from that on sapphire substrate that yields a vertical thin film device structure which has many unique features.