Efficiency droop in AlGaInP and GaInN light-emitting diodes

Shim, Jong‐In; Han, Dong‐Pyo; Kim, Hyunsung; Shin, Dong Soo; Lin, Guan-Bo; Meyaard, David S.; Shan, Qifeng; Cho, Jaehee; Schubert, E. Fred; Shim, H.W.; Sone, Cheolsoo

doi:10.1063/1.3694044

Cited by 67 publications

(49 citation statements)

References 18 publications

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“…The green LEDs that have lower p p0 , µ p , and a higher δ value than the blue LEDs' counterparts should have not only a larger C DL , but also a lower J Onset-of-droop , according to Equations (1) and (2). The onset of the efficiency droop is observed at current densities of 2.96 A/cm 2 for the blue LED and 0.33 A/cm 2 for the green LED, consistent with our expectation, and with results reported in the technical literature [26][27][28][29]. It is worthwhile to note that the green LEDs typically have a higher SRH non-radiative recombination coefficient A SRH than the blue LEDs, because of more defect sites in the epitaxial films caused by the larger lattice mismatch between the GaInN well and GaN barrier [30].…”

Section: Resultssupporting

confidence: 81%

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

et al. 2017

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Abstract:The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage of high injection, the onset current density of the droop, and the magnitude of the droop, as well as their temperature dependence, of GaInN-based blue and green light-emitting diodes (LEDs). An n-to-p asymmetry factor is defined as σ n /σ p , and was found to be 17.1 for blue LEDs and 50.1 for green LEDs. Green LEDs, when compared to blue LEDs, were shown to enter the high-injection regime at a lower voltage, which is attributed to their less favorable p-type transport characteristics. Green LEDs, with lower hole concentration and mobility, have a lower onset current density of the efficiency droop and a higher magnitude of the efficiency droop when compared to blue LEDs. The experimental results are in quantitative agreement with the imbalanced carrier transport causing the efficiency droop, thus providing guidance for alleviating the phenomenon of efficiency droop.

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Section: Resultssupporting

confidence: 81%

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

et al. 2017

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“…In a recent publication, Shim et al also suggested the possibility of a current dependent shift of the mean position of recombination for InGaAlPLEDs under electric current. 13 In our case, we treat the case of optical excitation of an InGaAlP-LED structure. Figure 6 shows the simulated inhomogeneous distribution of the radiative recombination rate for varying bias under constant laser excitation and for varying laser intensity under constant bias, respectively.…”

Section: Discussionmentioning

confidence: 99%

Unravelling concurring degradation mechanisms in InGaAlP light-emitting diode structures by optical overstress experiments under reverse bias

Karl

Ebbecke

Zeisel

et al. 2013

Journal of Applied Physics

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We examine the influence of an applied reverse bias on the optically induced and measured photoluminescence degradation characteristics of an InGaAlP light-emitting diode (LED) structure. We show that a reverse bias applied simultaneously to laser excitation of the sample has a strong impact on the observable photoluminescence degradation properties of the structure investigated via intense laser excitation. With the help of this approach, it is possible to control the carrier density and the internal electric field of the diode independently. By doing this, a distinction of several usually interfering photoluminescence degradation mechanisms from each other is achievable. Further, a comparison of the experimental data with simulated data delivers some indication on the local origin of the defect evolution processes within the light-emitting diode structure.

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“…The asymmetric shapes and the slope variation of the short-wavelength edge of the emission spectrum with current shown in Fig.2a, can be attributed to increasing junction temperature 13 . To further investigate into behaviour of the peak wavelength and spectral width, the EL intensity evolution during the microsecond current pulses was monitored via photodiode response under the same operating conditions, as shown in Fig.2d.…”

Section: Spectral Behaviourmentioning

confidence: 95%

“…At low current densities, carrier leakage due to asymmetric p-n junction has been suggested to contribute towards efficiency decrease in AlGaInP LEDs 12,13 . Comprehensive studies of internal quantum efficiency (IQE) of amber/red AlGaInP LEDs 14,15 have attributed the leakage to insufficiently high barriers separating quantum wells (QWs) in the LED active regions.…”

Section: Introductionmentioning

confidence: 99%

AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

et al. 2016

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Efficiency of commercial 620 nm AlGaInP Golden Dragon-cased high-power LEDs has been studied under extremely high pump current density up to 4.5 kA/cm 2 and pulse duration from microsecond down to sub-nanosecond range. To understand the nature of LED efficiency decrease with current, pulse width variation is used. Analysis of the pulse-duration dependence of the LED efficiency and emission spectrum suggests the active region overheating to be the major factor controlling the LED efficiency reduction at CW and sub-microsecond pumping. The overheating can be effectively avoided by the use of sub-nanosecond current pulses. A direct correlation between the onset of the efficiency decrease and LED overheating is demonstrated.

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Efficiency droop in AlGaInP and GaInN light-emitting diodes

Cited by 67 publications

References 18 publications

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

Unravelling concurring degradation mechanisms in InGaAlP light-emitting diode structures by optical overstress experiments under reverse bias

AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

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