Enhancement of InGaN-Based Light Emitting Diodes Performance Grown on Cone-Shaped Pattern Sapphire Substrates

To enhance light extraction effciency, high-quality InGaN-based light emitting diodes (LED) was grown on cone-shaped patterned sapphire (CPSS) by using metal organic chemical vapor deposition (MOCVD). From the transmission electron microscopy (TEM) observation, the CPSS was confirmed to be an efficient way to reduce the threading dislocation density in the GaN epilayer. A sharp and high intensity Photoluminescence (PL) for LED on CPSS at 457 nm compared to LED on unpattern planar sapphire substrates (USS) indicates that the crystalline quality was improved significantly and the internal reflection on the cones of the substrate was enhanced. The output power of the LED on CPSS is higher than that of LED on USS. The achieved improvement of the output power is not only due to the improvement of the internal quantum efficiency upon decreasing the dislocation density, but also due to the enhancement of the extraction efficiency using the CPSS.