Photometric figures of merit for semiconductor luminescent sources operating in spontaneous mode

Carr, W.N.

doi:10.1016/0020-0891(66)90019-4

Cited by 63 publications

(14 citation statements)

References 12 publications

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“…Since, in this paper, we are not concerned with the angular distribution of the emission a far-field transformation is not performed on this data. The power flows within the bulk and substrate layers are denoted by and respectively and the total power flow out of the simulation is given by (1) The power out of each layer is normalised to the total power to ensure a sum of unity in each simulation.…”

Section: Fdtd Modelmentioning

confidence: 99%

“…In a typical semiconductor light emitting diode (LED) structure the difference in refractive index at the interface between the device and the surrounding medium 2.5-results in a large amount of the generated optical power being trapped within the device. This is chiefly due to total internal reflection (TIR) which imposes an approximate limit of on the extraction efficiency of the device [1]. Moreover, for light incident within the escape cone at the dielectric interface formed by TIR further Fresnel reflection will occur.…”

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confidence: 99%

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Finite-Difference Time-Domain Modeling of Periodic and Disordered Surface Gratings in AlInSb Light Emitting Diodes With Metallic Back-Reflectors

Buss

Nash

Rarity

et al. 2010

J. Lightwave Technol.

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Abstract-Two-dimensional finite-difference time-domain modeling is undertaken to study the optical behaviour of midinfrared AlInSb light-emitting diode devices with close metallic back reflectors. The location of the source and mirror is investigated in detail and optimised for peak emission at 0 = 4 m. A periodic surface grating is added and it is found that greater than 98% of the light at a specific wavelength may be extracted for specific grating parameters, an enhancement of 20-fold. A novel type of grating termed disordered-periodic is then studied and is shown to have a much broader spectral response with more than 50% of the power extracted across a broad wavelength range.

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Section: Fdtd Modelmentioning

confidence: 99%

mentioning

confidence: 99%

Finite-Difference Time-Domain Modeling of Periodic and Disordered Surface Gratings in AlInSb Light Emitting Diodes With Metallic Back-Reflectors

Buss

Nash

Rarity

et al. 2010

J. Lightwave Technol.

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“…This function represents the number of photon generated per unit volume per unit time, and may be evaluated by a self-consistent method. In the first approximation we write the generation rate as g (1) (x, e), and do not consider re-excitation. This function £ (1) is then used to determine the photon absorption rate v(x, e) giving the number of photons absorbed per unit volume per unit time.…”

Section: Theory Of Re-excitationmentioning

confidence: 99%

“…In the first approximation we write the generation rate as g (1) (x, e), and do not consider re-excitation. This function £ (1) is then used to determine the photon absorption rate v(x, e) giving the number of photons absorbed per unit volume per unit time. This value of photon absorption rate is then used to find the second approximation to the generation rate g^2 ) (x,e) from a modified continuity equation, and taking into account the first approximation of the photon absorption rate.…”

Section: Theory Of Re-excitationmentioning

confidence: 99%

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Effect of feedback carrier excitation on LED external quantum efficiency

Kučera

Macháč

Míšek

1982

IEE Proc. I Solid State Electron. Devices UK

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Self-absorption of photons generated by prior luminescence processes affects both the steady-state and transient characteristics of LEDs. In this study we confine ourselves to one of the most important steadystate parameters -external quantum efficiency. It is shown that the photon self-absorption increases the injected carrier concentration, and consequently the emitted photon flux. This results in an increase in LED external quantum efficiency. A detailed analysis of this phenomenon is presented, and a simplified evaluation of its influence on the external quantum efficiency is given. Our calculation also takes into account multiple internal reflection of light generated inside the LED. The obtained results are applied to a diffused GaAs (Zn, Te) surface-emitting LED. It is estimated that the feedback carrier excitation (re-excitation) due to selfabsorption increases the LED external quantum efficiency by about 60% and multiple internal reflections by about 12%. IntroductionIn an LED with a direct bandgap structure, a large number of photons generated by luminescence processes are subsequently reabsorbed within the LED' analysed the contribution of the re-excitation to the external quantum efficiency of GaAs-Al^Gaj _ x As heterostructures [4]. The influence of re-excitation on diffusion lengths of minority carriers and the minority-carrier concentration distribution in GaAs epitaxial layers excited by intensive light beam has been studied by Epifanov et al. [5]. The influence on emission spectrum shape has also been studied [6].In our paper a theoretical model of re-excitation is studied. The main purpose has been to describe the influence of the re-excitation on the LED external quantum efficiency. The presented theory also includes multiple reflections of light generated in the diode, as this effect cannot be neglected in many LED structures. Theory of re-excitationIn any analysis of re-excitation we need to determine the photon generation rate g(x, e), where x is the position and e is the photon energy. This function represents the number of photon generated per unit volume per unit time, and may be evaluated by a self-consistent method. In the first approximation we write the generation rate as g (1) (x, e), and do not consider re-excitation. This function £(1) is then used to determine the photon absorption rate v(x, e) giving the number of photons absorbed per unit volume per unit time. This value of photon absorption rate is then used to find the second approximation to the generation rate g^2 ) (x,e) from a modified continuity equation, and taking into account the first approximation of the photon absorption rate. The procedure may be repeated to find a new photon absorption rate and a third approximation to the generation rate. It may be shown that the third approximation does not contribute tothe generation rate significantly. For practical purposes then, it is sufficient to confine this procedure to the first two steps and to consider the function g (2) as the resultant function, the super...

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Diodes, Light‐emitting

Gardner¹,

Craford²,

Steranka³

2004

Digital Encyclopedia of Applied Physics

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A light‐emitting diode (LED) is a semiconductor device that emits monochromatic ultraviolet, visible, or infrared electromagnetic radiation when an electric current is passed through it. The semiconductor material is a compound or alloy of elements from columns III and V of the periodic table. Light‐emitting diodes are compact, mechanically rugged, energy efficient, are of low voltage, and have long operating lifetimes. For colored lighting applications, the efficiency of LEDs far exceeds that of filtered incandescent sources and they are becoming the dominant technology. LEDs are widely used as indicator lights, for backlighting small displays in electronic equipment, in exterior and interior lighting of automobiles, in large‐area full‐color displays, and for data communication. LEDs will be used for general white‐light illumination purposes to the extent that the energy efficiency improves and higher‐power, higher‐flux devices become available.

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Photometric figures of merit for semiconductor luminescent sources operating in spontaneous mode

Cited by 63 publications

References 12 publications

Finite-Difference Time-Domain Modeling of Periodic and Disordered Surface Gratings in AlInSb Light Emitting Diodes With Metallic Back-Reflectors

Finite-Difference Time-Domain Modeling of Periodic and Disordered Surface Gratings in AlInSb Light Emitting Diodes With Metallic Back-Reflectors

Effect of feedback carrier excitation on LED external quantum efficiency

Diodes, Light‐emitting

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