Theoretical and experimental analysis of current spreading in AlGaInP light emitting diodes

Perks, Richard Marc; Porch, Adrian; Морган, Д.; Kettle, Jeff

doi:10.1063/1.2358396

Cited by 11 publications

(6 citation statements)

References 9 publications

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“…As a matter of fact, it was shown that, in vertical LEDs, CC causes such negative effects on their performance, as it does in their lateral counterparts. Moreover, the recent studies suggest the existence of CC in AlGaInP LEDs [5], [9], [10]. Meanwhile, in all these researches, the impact of CC on the performance of vertical red LEDs grown on conductive substrates has not been reported in details in comparison to the avalanche of papers related to this effect in lateral blue InGaN LEDs grown on sapphire.…”

Section: Introductionmentioning

confidence: 92%

“…Three types of devices with different p-contact shapes depicted as LED1, LED2, and LED3 were studied ( the emitting area. Such a contact shape is typical of commercial devices and traditionally has been a model for studies of the CC [5], [9]. The LED2 and LED3 1 1 mm in size had circular p-contacts 100 m in diameter and four crossed 30-m-wide contact stripes.…”

Section: Device Designmentioning

confidence: 99%

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Research on Performance of Red Vertical AlGaInP/GaAs Light-Emitting Diodes Influenced by Current Crowding

Malyutenko

Bolgov

Tykhonov

et al. 2011

IEEE Photon. Technol. Lett.

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The authors show that the performance of red vertical AlGaInP/GaAs light-emitting diodes is compromised by the current crowding (CC) effect in the moderate-current (space charge region dominates in the device performance) and high-current (series resistance dominates in the equivalent circuit of a device) domains. Depending on the contact pattern, a remarkable part of the performance degradation comes as a result of the electrical power lost on the series resistance ( 17%). CC affects the ideality factor and causes the current spreading length to decrease from 425 m at low currents to 75 m at a current of 250 mA.

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Section: Introductionmentioning

confidence: 92%

Section: Device Designmentioning

confidence: 99%

Research on Performance of Red Vertical AlGaInP/GaAs Light-Emitting Diodes Influenced by Current Crowding

Malyutenko

Bolgov

Tykhonov

et al. 2011

IEEE Photon. Technol. Lett.

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“…In most cases, shortcomings are related to the removal of heat, 3 which is due to the JH of the structure and increased rate of nonradiative Auger recombination of injected charge carriers. In our opinion, the appearance of the current crowding ͑CC͒ effect, 4 which is rarely mentioned in AlGaAs/GaAs structures 5 but is well established in less efficient blueshifted [6][7][8] and redshifted [9][10][11][12] LEDs, should also be considered. This effect is due to the localization of the current flow rout in some regions of a multilayer LED structure whose position and geometry are difficult to predict a priori.…”

Section: Introductionmentioning

confidence: 99%

The effect of current crowding on the heat and light pattern in high-power AlGaAs light emitting diodes

Zinovchuk

Malyutenko

et al. 2008

Journal of Applied Physics

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The results of the light and temperature micromapping in AlGaAs light emitting diodes grown by liquid phase epitaxy as double heterostructures and emitting at ϳ 0.87 m are presented. At a driving current well above the safe operating limit ͑Ͼ300 mA͒, the nonuniform light pattern and local self-heating ͑with temperature gradient of about 950°C / cm͒ followed by catastrophic degradation of a device were detected with the charge coupled device and infrared microscopes operating in a pulsed mode. These were shown to result from the current crowding effect in the active and contact areas of a device. Good agreement between the theory and experiment was found.

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“…The current crowding effect is well known in LEDs operating in both visible (based on InGaN [1] and AlGaInP [2]) and IR (InAsSb [3]) spectral intervals. Several investigations have been devoted to numerical simulation [4,5] and analytical modeling [1,6,7] of current spreading in LEDs. These works were aimed at improvement of current spreading in the active region of devices through optimization of the internal param eters (resistance and thickness of the substrate, con finement layers, and current spreading layers) and the geometry of contacts.…”

mentioning

confidence: 99%

The effect of current crowding on the internal quantum efficiency of InAsSb/InAs light-emitting diodes

Kudryk

Zinovchuk

2012

Tech. Phys. Lett.

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A general problem for light emitting diodes (LEDs) operating in various spectral intervals is related to the phenomenon of "crowding" of the cur rent lines in some regions of a multilayer LED struc ture, which is caused by rather high resistivities of lay ers and specific features of the LED exterior design that are determined by the need to extract radiation. The current crowding effect is well known in LEDs operating in both visible (based on InGaN [1] and AlGaInP [2]) and IR (InAsSb [3]) spectral intervals. Several investigations have been devoted to numerical simulation [4,5] and analytical modeling [1,6,7] of current spreading in LEDs. These works were aimed at improvement of current spreading in the active region of devices through optimization of the internal param eters (resistance and thickness of the substrate, con finement layers, and current spreading layers) and the geometry of contacts. It was also pointed out that cur rent crowding led to the activation of nonradiative recombination, local heating of the device structure, and a resulting decrease in the IQE of LEDs. However, no quantitative calculations of the influence of current crowding on the IQE have been performed so far.Because of the dominant role of nonradiative recombination in narrow bandgap semiconductors, the current crowding effect must be especially pro nounced in LEDs operating in the mid IR range. For this reason, we have studied mid IR LEDs based on InAsSb/InAs heterostructures, the production tech nology and main performance parameters of which are well known (see, e.g., [8,9]). This Letter presents the results of calculations of the IQE of InAsSb/InAs LEDs as a function of the injection level with allow ance for the current crowding effect.We have considered InAsSb/InAs LEDs of stan dard planar design with a round n contact of radius r 0 = 50 μm on the upper surface (Fig. 1a). The spatial distributions of current density were performed by assuming axial symmetry of the structure (LEDs have a cylindrical shape with external radius R = 300 μm). Taking into account data [8] on the internal structure of InAsSb/InAs LEDs, the proposed model takes into account the three most important layers, which are characterized by their thicknesses and resistivities: p InAs substrate (d p , ρ π ), n InAsSb active layer (d al , ρ al ), and upper n InAsSbP spreading layer (d n , ρ n ). Calculations were performed for the following numer ical values of these parameters:d n = 5 μm, ρ n = 6.2 × 10 -4 Ω cm; d p = 200 μm, ρ p = 4.1 × 10 -2 Ω cm; and d al = 2 μm. It is assumed that the active layer is characterized by a nonlinear resistance of the p-n junction, which is calculated using the diode current-voltage character istic as follows:where ϕ al is the voltage drop on the active layer, k is the Boltzmann constant, T is the absolute temperature, e is the electron charge, β is the ideality factor of the p-n junction, and j 0 is the saturation current density. All calculations were performed for β = 1, T = 300 K, and the saturation current density j 0 ...

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Theoretical and experimental analysis of current spreading in AlGaInP light emitting diodes

Cited by 11 publications

References 9 publications

Research on Performance of Red Vertical AlGaInP/GaAs Light-Emitting Diodes Influenced by Current Crowding

Research on Performance of Red Vertical AlGaInP/GaAs Light-Emitting Diodes Influenced by Current Crowding

The effect of current crowding on the heat and light pattern in high-power AlGaAs light emitting diodes

The effect of current crowding on the internal quantum efficiency of InAsSb/InAs light-emitting diodes

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