Spontaneous emission model of lateral light extraction from heterostructure light-emitting diodes

Ochoa, D.; Houdré, R.; Stanley, R. P.; Ilegems, M.; Bénisty, Henri; Hanke, C.; Borchert, B.

doi:10.1063/1.126622

Cited by 8 publications

(6 citation statements)

References 8 publications

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“…The transmission in the simulation is in proportion to the extraction efficiency of LEDs, even though the photon recycling effect can increase the extraction efficiency by a little. 15,16) We can simulate the relative variation of the extraction efficiency by measuring the energy flux along the half circle in the upper medium and the energy flux along the full circle.…”

Section: Numerical Setupmentioning

confidence: 99%

Analysis of the Effect of Surface Texture in Light-Emitting Diodes Based on a Finite-Difference-Time-Domain Method

Lee

2007

jjap

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We used a two-dimensional finte-difference-time-domain (FDTD) method to study the effect of surface texture in light-emitting diodes (LEDs). Surface texture is implemented as a rectangular groove, dividing the high index medium and the low index medium. The transmission efficiency of the dipole source located in the high refractive index medium is measured with various parameters of the rectangular groove. The transmission efficiency of the roughened surface increases about 36% compared to that of the smooth surface. As for the period of the groove ranging from 0.5λ to 2.5λ, the efficiency does not show much dependency on the period or duty cycle. On the other hand, the transmission increases with the depth of the grooves. Extraction efficiency improves 78% when the depth of the grooves reaches twice the period. The amount of efficiency increase is significant considering that the grating period is much larger than that of photonic crystals. Furthermore, the weak dependency of transmission efficiency on the period and on the duty cycle of the grooves may alleviate processing difficulties by increasing fabrication tolerance of surface texture.

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Section: Numerical Setupmentioning

confidence: 99%

Analysis of the Effect of Surface Texture in Light-Emitting Diodes Based on a Finite-Difference-Time-Domain Method

Lee

2007

jjap

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“…Light going into the guided mode (see Section 2.4) is more subject to this absorption, leading to the recycling effect: photons from the high-energy part of the emission spectrum can be absorbed into the active zone by creating electron-hole pairs that, in turn, can recombine radiatively and emit photons. This effect on the external quantum efficiency is proportional to (1 − η int η abs ) −1 [29], where η int is the internal quantum efficiency of the active zone, and η abs is the fraction of reabsorbed light. It appears that the efficiency increase is only important for high quality active zones, when η int is close to unity.…”

Section: Absorption Into the Active Zonementioning

confidence: 99%

“…Our simulation model takes into account the lateral propagation of the guided mode and gives access to the lateral extraction factor, the amount of light absorbed in the QWs [29], and therefore the recycling factor.…”

Section: Realistic Mcledmentioning

confidence: 99%

Microcavity light emitting diodes as efficient planar light emitters for telecommunication applications

Ochoa

Houdré

Ilegems

et al. 2002

Comptes Rendus. Physique

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Light emitting diodes (LEDs) can be coupled to optical fibers and used in telecommunication applications. Compared to laser diodes, the coupling is usually small, due to the isotropic emission of the source, combined with the large refractive index difference between the semiconductor and the outside medium. However, it is possible to greatly enhance the optical extraction of a planar LED by placing the source inside a microcavity which optical thickness is close to the wavelength of the emitted light. Some elementary design rules of a microcavity light emitting diode (MCLED) are explained here, and are illustrated on a real GaAs/Al x Ga 1−x As device emitting at 880 nm. The surface external quantum efficiency of this MCLED reaches 14% into air and 20.6% with an encapsulation into an epoxy lens. These values are about 10 times larger than for a usual LED and are in good agreement with theoretical values, calculated with a plane waves model. To cite this article: D. Ochoa et al., C. R. Physique 3 (2002) 3-14.  2002 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS light emitting diode / microcavity / brightness / Fabry-Pérot / semiconductors La diode électroluminescente à microcavité : un émetteur de lumière planaire efficace pour des applications en télécommunications Résumé Les diodes électroluminescentes (LEDs) peuvent être couplées à des fibres optiques et utilisées pour des applications en télécommunications. Ce couplage est généralement assez faible, en comparaison de celui qui est obtenu avec des diodes laser. Ceci est dû principalement à l'émission isotropique de la source, combinée à la grande différence d'indice de réfraction entre le semiconducteur et le milieu extérieur. Cependant, l'extraction optique d'une LED planaire peut être largement augmentée si la source est placée à l'intérieur d'une microcavité dont l'épaisseur est proche de la longueur d'onde de la lumière émise. Nous expliquons ici quelques règles fondamentales de conception d'une LED à microcavité (MCLED), et nous les illustrons avec l'exemple d'un composant réel en GaAs/Al x Ga 1−x As, émettant à 880 nm. Le rendement quantique externe de cette MCLED atteint 14% pour une emission dans l'air et 20,6% avec une encapsulation dans une lentille en époxy. Ces valeurs sont près de dix fois supérieures à celles d'une LED standard, et sont

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“…19 In a MCLED, the optically active region is placed at an antinode position inside a FabryPerot thin cavity, which size is close to the wavelength of the emitted light. One of the few resonant modes of the Fabry-Pérot is resonant in a direction which is almost normal to the surface of the device.…”

Section: Introductionmentioning

confidence: 99%

880-nm surface-emitting microcavity light-emitting diode

et al. 2001

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Microcavity light emitting diodes (MCLEDs) are planar emitting devices that can achieve large brightness increase compare to conventional LEDs. We designed and fabricated a GaAs/A1Gai_As surface-emitting MCLED emitting at 880nm. Two InGaAs quantum wells are included in a A-A103Ga07As cavity between two A1o.iGao9As/Alo.8Gao.2AsBragg mirrors. The top n-doped Bragg mirror has 4 pairs, the bottom one is p-doped like the substrate and has 20 pairs. The detuning between the source emission wavelength and the Fabry Perot wavelength is -2Onm. It is optimum for an extraction into air. By inserting the bonded MCLED device into an integration sphere we measured a maximum external quantum efficiency of 14% at 10 mA. An epoxy lens is placed on top of the device and the external quantum efficiency is increased up to 20.5% at 10 mA. These values are in good agreement with theoretical calculations if the internal quantum efficiency of the structure is equal to 85%. Additional calculations and measurements are performed and lead to a good physical understanding of the MCLED.

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Spontaneous emission model of lateral light extraction from heterostructure light-emitting diodes

Abstract: Improvement in spontaneous emission rates for InGaN quantum wells on ternary InGaN substrate for lightemitting diodesHigh spontaneous emission rate asymmetrically graded 480 nm InGaN/GaN quantum well light-emitting diodes

Cited by 8 publications

References 8 publications

Analysis of the Effect of Surface Texture in Light-Emitting Diodes Based on a Finite-Difference-Time-Domain Method

Analysis of the Effect of Surface Texture in Light-Emitting Diodes Based on a Finite-Difference-Time-Domain Method

Microcavity light emitting diodes as efficient planar light emitters for telecommunication applications

880-nm surface-emitting microcavity light-emitting diode

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