Optimization of Light-Diffracting Photonic-Crystals for High Extraction Efficiency LEDs

Directional emission control and increased light extraction in GaN photonic crystal light emitting diodes

“…However, improvements in PhC GaN LEDs have been limited to factors of ϳ1.5-2 times 12-15 despite much higher increases predicted theoretically. 16 These limitations are due in part to an unoptimized vertical design that does not achieve maximum interaction of the guided modes with the PhC and the use of nonoptimal lattice constants.…”

Ga N ∕ In Ga N light emitting diodes with embedded photonic crystal obtained by lateral epitaxial overgrowth

“…[3][4][5][6][7][8] However, harnessing the full potential of PhCs has proved difficult: the largest light extraction enhancements reported in the literature are approximately twice, which are largely below theoretical expectations. Indeed, efficient PhCs require full optimization of the design, 9 including choices of the crystal lattice 6 and of the vertical structure. 7,8 In particular, Ref.…”

High extraction efficiency light-emitting diodes based on embedded air-gap photonic-crystals

“…1͑b͒ are due to the change on the mode order of the CLM as the thickness of the cavity varies and the oscillations represent variations in the vertical resonances of the Bloch mode with the PhC layer. 11 The optimal PhC fill factor for a 540 nm-thick cap layer and 100 nm-thick embedded PhC layer was found to be around 14%. Both low fill factor and thin embedded PhCs result in weak confinement of modes in the cap layer ͑or equivalently, in the bottom GaN layer below the PhCs͒.…”