ABSTRACT
Realizing lighting sources that are efficient, affordable, and environmentally friendly is one of the major goals of research and development of III-nitride light-emitting diodes (LEDs). Only about 5% of light produced in these materials escapes out in to air, the remaining is mostly guided laterally and eventually absorbed. Photonic crystals (PCs) have attracted intensive interest in scientific research and technical applications, because they offer approaches to manipulate photons, allowing the control of light propagation. Of the many other potential practical applications, using PC to dramatically increase light extraction efficiency of LEDs is very promising. The proceeding work reviews some of the pioneering work undertaken in incorporating PCs in the III-nitride LEDs for the purpose of enhancing light extraction. The incorporation of PC into both blue and ultraviolet (UV) nitride LEDs resulted in enhancement in extraction efficiency, light emission direction,
and pattern control and modulation speed control. More recent developments have showed that embedding 2D PCs in LEDs further enhances extraction efficiency because of improved interaction with guided modes. PC LEDs have become commercially available for high-end products. In addition several groups have started to explore III-nitride PC surface-emitting lasers, PC micro-and nanocavities, and microdisk lasers.
