Photonic crystal LEDs – designing light extraction

Laser & Photon. Rev. 3, No.3, 262–286 (2009) / DOI 10.1002/lpor.200810053Abstract Photonic crystals (PhCs) have attracted much atten-tion during the last decade as a solution to overcome the lowextraction efficiency of as-grown light-emitting diodes (LEDs).In this review we describe the underlying physics and summa-rize recent results obtained with PhC LEDs. Here, the mainfocus is on diffracting PhC. In order to quantify the benefit fromthe incorporation of PhCs for diffracting light a comparison bysimulations between a PhC LED and a standard state-of-the-art LED is carried out. Finally, the impact of the PhC on theLEDs emission characteristics will be discussed with respect toetendue-limited applications.´Azimuthal emission pattern of an InGaN/GaN LED with hexag-onal PhC at a single wavelength. Background: SEM (scanningelectron microscope) image of the PhC structure.