Crystal Quality and Light Output Power of GaN-Based LEDs Grown on Nanoporous Patterned Sapphire Substrate

Abstract

Abstract: The crystal quality and light output power of GaN-based light-emitting diodes (LEDs) grown on concave patterned sapphire substrate (CPSS) were investigated. It was found that the crystal quality of GaN-based LEDs grown on CPSS improved with the decrease of the pattern space (percentage of c-plane). However, when the pattern space decreased to 0.41 μm (S0.41-GaN), the GaN crystallinity dropped. On the other hand, the light output power of GaN-based LEDs was incr eased with the decrease of the pattern space due to the change of the light extraction efficiency. Keywords: GaN-based LED; concave patterned sapphire substrate; crystal quality; light output power 1. Introduction High-brightness GaN-based light-emitting diode (LED) is widely used in variety of applications for their versatile functions like the display screen s, mobile phones, automobile headlights, etc. The external quantum efficiency (EQE) is a functi on of both the internal quantum efficiency (IQE) and light extraction efficiency (LEE). While the GaN-based LEDs posses hi gh luminescence efficiency they still suffer from