High-brightness InGaAlP green light-emitting diodes

Sugawara, Hideto; Itaya, Kazuhiko; Nozaki, Hidetoshi; Hatakoshi, Gen–ichi

doi:10.1063/1.108423

Cited by 81 publications

(17 citation statements)

References 10 publications

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“…A GaP current-spreading layer in an AlGaInP LED was reported by Kuo et al [26] and Fletcher et al [27,28]. AlGaAs current-spreading layers in AlGaInP LEDs were reported by Sugawara et al [29][30][31]. 16 For circular contact geometry, the thickness of the current spreading layer, t, results a current-spreading length L s given by [32] …”

Section: Current Transport In Led Structuresmentioning

confidence: 99%

Inorganic Semiconductors for Light‐emitting Diodes

Schubert

Gessmann

Kim

2005

Organic Light Emitting Devices

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Section: Current Transport In Led Structuresmentioning

confidence: 99%

Inorganic Semiconductors for Light‐emitting Diodes

Schubert

Gessmann

Kim

2005

Organic Light Emitting Devices

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“…Although the basic DH structure may be very efficient at generating light, efficient extraction of photons from the high-index semiconductor (n~3.5) in a practical device is a challenging problem. Various techniques have been developed including: growth of a thick p-type GaP layer on the p-type confining layer to aid in current-spreading and light extraction; 7 insertion of a DBR below the DH; 8 and complete separation of the epitaxial layers from the GaAs substrate followed by wafer-bonding to a transparent GaP substrate to reduce absorption and enable extraction of light from all surfaces of the device. 9 The basic issues of carrier injection, confinement, and radiative recombination are critical factors which affect the overall device efficiency (brightness).…”

Section: Introductionmentioning

confidence: 99%

Oxygen incorporation in AllnP, and its effect on P-type doping with magnesium

Stockman

Huang

Osentowski

et al. 1999

J. Electron. Mater.

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Oxygen incorporation in Al y In 1-y P (y ~ 0.5) grown by metalorganic chemical vapor deposition (MOCVD) has been studied as a function of PH 3 flow, growth temperature, and alloy composition. Both O 2 and diethylaluminum ethoxide (DEAlO) were employed as sources of oxygen. The incorporation of oxygen was found to be a superlinear function of O 2 or DEAlO flow. When multiple sources of oxygen are present, a surface interaction leads to enhanced oxygen incorporation. Oxygen incorporation cannot be adequately described by a simple dependence on growth temperature or V/III ratio due to strong interactions between these variables. In Mg-doped AlInP co-doped with oxygen, the incorporation of both Mg and O is strongly affected by an interaction between the two species, and roughly 10% of the oxygen atoms act as compensating donors.

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“…The large refractive index difference between the semiconductor chip and air or the epoxy dome limits the extraction efficiency for a basic LED structure to just a few percent due to total internal reflection. Some of the techniques aimed at increasing the extraction efficiency of LEDs include surface texturing [24][25][26] , micro-patterning [27][28][29][30][31] , 1D and 2D photonic crystals [32][33][34][35][36][37][38][39] , chip-shaping [40][41][42] , and remote phosphor design [43,44] . Although some of these techniques can increase the extraction efficiency to 50% or even higher, many are optimized for a single wavelength for use in monochromatic LEDs.…”

Section: Device Efficiencymentioning

confidence: 99%

Efficiency improvements of white-light CdSe nanocrystal-based LEDs

et al. 2007

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We have recently demonstrated white-light devices based on single size, ultra-small cadmium selenide (CdSe) nanocrystals that possess broadband emission (420-710 nm). When encapsulated in a polymer and coated on commercial UV LEDs, these nanocrystals act as frequency downconverters to produce high quality white light. These devices emit very pure white light with excellent CIE coordinates (0.35, 0.31) and a very high color rendering index of 93 when excited with a 365 nm LED. The relatively low luminous efficiency of preliminary devices, up to 1 lm/W, is a result of unoptimized device geometry, low light extraction efficiency, low UV LED efficiency, and low nanocrystal quantum yield (~10%). In order to address the issue of efficiency, we have pursued two studies. First, we investigate the use of photonic crystal mirrors, chirped mirrors, and thin film filters to increase the extraction efficiency and decrease UV light leakage from the device. Simulation results of chirped mirrors consisting of alternating layers of silicon dioxide (SiO 2 ) and hafnium dioxide (HfO 2 ) have demonstrated high reflectance throughout the visible region, thus increasing extraction efficiency by reflecting emitted white light out of the device that would normally be lost. Second, we examine the tradeoff of color quality and efficiency that results from using blue LEDs for excitation: unabsorbed blue light will imbalance the white-light spectrum, but the conversion of blue to white light yields a lower Stokes loss than UV excitation light.

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High-brightness InGaAlP green light-emitting diodes

Cited by 81 publications

References 10 publications

Inorganic Semiconductors for Light‐emitting Diodes

Inorganic Semiconductors for Light‐emitting Diodes

Oxygen incorporation in AllnP, and its effect on P-type doping with magnesium

Efficiency improvements of white-light CdSe nanocrystal-based LEDs

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