On the symmetry of efficiency-versus-carrier-concentration curves in GaInN/GaN light-emitting diodes and relation to droop-causing mechanisms

Dai, Qi; Shan, Qifeng; Cho, Jaehee; Schubert, E. Fred; Crawford, Mary H.; Koleske, Daniel; Kim, Minho; Park, Yongjo

doi:10.1063/1.3544584

Cited by 91 publications

(72 citation statements)

References 15 publications

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“…Our present results show that the rate of decrease of the Auger coefficient with density in the 2 × 10 18 − 5 × 10 19 cm −3 range (which includes the peak of the internal quantum efficiency of LEDs [9]) is smaller than the rate of decrease of the radiative coefficient (B) [36]. The more rapid decrease of the B coefficient in comparison to the C coefficient with increasing free-carrier density may explain the asymmetry of the internal quantum efficiency curve reported in the literature [68], without invoking an additional fourth-order or higher-power carrier-loss mechanism.…”

Section: Due To (A) Electron-electron-hole (E-e-h) and (B) Hole-hole-mentioning

confidence: 72%

First-principles calculations of indirect Auger recombination in nitride semiconductors

et al. 2015

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Auger recombination is an important nonradiative carrier recombination mechanism in many classes of optoelectronic devices. The microscopic Auger processes can be either direct or indirect, mediated by an additional scattering mechanism such as the electron-phonon interaction and alloy disorder scattering. Indirect Auger recombination is particularly strong in nitride materials and affects the efficiency of nitride optoelectronic devices at high powers. Here, we present a first-principles computational formalism for the study of direct and indirect Auger recombination in direct-band-gap semiconductors and apply it to the case of nitride materials. We show that direct Auger recombination is weak in the nitrides and cannot account for experimental measurements. On the other hand, carrier scattering by phonons and alloy disorder enables indirect Auger processes that can explain the observed loss in devices. We analyze the dominant phonon contributions to the Auger recombination rate and the influence of temperature and strain on the values of the Auger coefficients. Auger processes assisted by charged-defect scattering are much weaker than the phonon-assisted ones for realistic defect densities and not important for the device performance. The computational formalism is general and can be applied to the calculation of the Auger coefficient in other classes of optoelectronic materials.

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Section: Due To (A) Electron-electron-hole (E-e-h) and (B) Hole-hole-mentioning

confidence: 72%

First-principles calculations of indirect Auger recombination in nitride semiconductors

et al. 2015

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“…1. To reveal the root cause of the discrepancies between the computed and measured results, especially for the 11-QW LED device, the well-known ABC model [17] …”

Section: Resultsmentioning

confidence: 99%

Nonradiative recombination — critical in choosing quantum well number for InGaN/GaN light-emitting diodes

Zhang¹,

Zhang²,

Liu³

et al. 2014

Opt. Express

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Abstract:In this work, InGaN/GaN light-emitting diodes (LEDs) possessing varied quantum well (QW) numbers were systematically investigated both numerically and experimentally. The numerical computations show that with the increased QW number, a reduced electron leakage can be achieved and hence the efficiency droop can be reduced when a constant Shockley-Read-Hall (SRH) nonradiative recombination lifetime is used for all the samples. However, the experimental results indicate that, though the efficiency droop is suppressed, the LED optical power is first improved and then degraded with the increasing QW number. The analysis of the measured external quantum efficiency (EQE) with the increasing current revealed that an increasingly dominant SRH nonradiative recombination is induced with more epitaxial QWs, which can be related to the defect generation due to the strain relaxation, especially when the effective thickness exceeds the critical thickness. These observations were further supported by the carrier lifetime measurement using a pico-second time-resolved photoluminescence (TRPL) system, which allowed for a revised numerical modeling with the different SRH lifetimes considered. This work provides useful guidelines on choosing the critical QW number when designing LED structures.

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“…7 For this reason, we extend the ABC model by adding another recombination term, f(n), to the model, where f(n) includes carrier leakage and is allowed to contain 2nd and 3rd, as well as higher order terms of n. Because of the ambiguity with respect to C and the 3rd order term of f(n), we will include both of these in f(n).…”

mentioning

confidence: 99%

“…In this article, we utilize the ABC þ f(n) model, where f(n) refers to additional non-radiative recombination mechanisms, such as leakage from the active region. 7 We then measure temperature dependent light output from a GaN/GaInN based LED and quantitatively extract the contribution of each carrier loss mechanism.…”

mentioning

confidence: 99%

On the temperature dependence of electron leakage from the active region of GaInN/GaN light-emitting diodes

Meyaard

Shan

Dai

et al. 2011

Applied Physics Letters

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Reduction in the light-output power in GaN-based light-emitting diodes (LEDs) with increasing temperature is a well-known phenomenon. In this work, temperature dependent external-quantum-efficiency versus current curves are measured, and the mechanisms of recombination are discussed. Shockley-Read-Hall recombination increases with temperature and is found to greatly reduce the light output at low current densities. However, this fails to explain the drop in light-output power at high current densities. At typical current density (35 A/cm2), as temperature increases, our results are consistent with increased Shockley-Read-Hall recombination and increased electron leakage from the active region. Both of these effects contribute to the reduction in light-output power in GaInN/GaN LEDs at high temperatures.

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On the symmetry of efficiency-versus-carrier-concentration curves in GaInN/GaN light-emitting diodes and relation to droop-causing mechanisms

Cited by 91 publications

References 15 publications

First-principles calculations of indirect Auger recombination in nitride semiconductors

First-principles calculations of indirect Auger recombination in nitride semiconductors

Nonradiative recombination — critical in choosing quantum well number for InGaN/GaN light-emitting diodes

On the temperature dependence of electron leakage from the active region of GaInN/GaN light-emitting diodes

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