Strain-induced defects as nonradiative recombination centers in green-emitting GaInN/GaN quantum well structures

Langer, Torsten; Jönen, H.; Kruse, Andreas; Bremers, Heiko; Rossów, U.; Hangleiter, A.

doi:10.1063/1.4813446

Cited by 77 publications

(60 citation statements)

References 17 publications

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“…Basically, the green-gap problem originates from the higher indium mole fraction in the GaInN quantum-well active region of green LEDs. The higher mole fraction increases the lattice mismatch with the adjacent GaN cladding layers and so the defect density, increases the mechanical strain [6] and the consequent quantum-confined Stark effect [7], and decreases thermal stability because of the decreased melting temperature [8]. Therefore, higher nonradiative and lower radiative recombination rates are expected, which lead to lower internal quantum efficiency (IQE) in longer wavelength LEDs with the higher indium mole fraction.…”

Section: Introductionmentioning

confidence: 96%

Current Components and Their Temperature Dependence of Green and Blue Light-Emitting Diodes: A Quantitative Comparison

Kim

Lee

Ryu

et al. 2014

IEEE Trans. Electron Devices

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We have quantitatively compared the portion and temperature dependence of each current component in commercial green and blue light-emitting diodes (LEDs) using a current-component analysis method for the purpose of finding out the origin of the green-gap problem, which is a major roadblock to the next-generation solid-state lighting. The analysis results show that the loss current, which is the origin of the efficiency droop, decreases the internal quantum efficiency of the green LED significantly and is the primary origin of the green-gap problem. In addition, the loss current I loss and the radiation current I rad that actually generates light output are approximately related as I loss ∝ I 1.5 rad almost independent of the temperature. Therefore, I loss and I 1.5 rad have the similar temperature dependence in both the green and blue LEDs, and the loss current is approximately proportional to the cube of the carrier concentration. The temperature and the carrierconcentration dependences are valuable clues to the physical origin of the green-gap problem and the efficiency droop. On the other hand, the portion and the temperature sensitivity of the Shockley-Read-Hall (SRH) nonradiative recombination current are similar in the green and blue LEDs. Therefore, in our samples, the SRH nonradiative recombination is not the origin of the green-gap problem.Index Terms-Current-voltage (I-V ) characteristics, green gap, light-emitting diodes (LEDs), quantum efficiency.

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Section: Introductionmentioning

confidence: 96%

Current Components and Their Temperature Dependence of Green and Blue Light-Emitting Diodes: A Quantitative Comparison

Kim

Lee

Ryu

et al. 2014

IEEE Trans. Electron Devices

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“…If the non-radiative recombination pathways are similar then it can be anticipated that the efficiency of green light emission would be less than that of blue emission. However, it has been reported 8,9 that this change in the radiative recombination lifetime is not sufficient to fully explain the reduction in efficiency. It has been suggested that there is also a reduction in the non-radiative recombination lifetime.…”

mentioning

confidence: 99%

Effects of quantum well growth temperature on the recombination efficiency of InGaN/GaN multiple quantum wells that emit in the green and blue spectral regions

Hammersley

Kappers

Massabuau

et al. 2015

Applied Physics Letters

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InGaN-based light emitting diodes and multiple quantum wells designed to emit in the green spectral region exhibit, in general, lower internal quantum efficiencies than their blue-emitting counter parts, a phenomenon referred to as the “green gap.” One of the main differences between green-emitting and blue-emitting samples is that the quantum well growth temperature is lower for structures designed to emit at longer wavelengths, in order to reduce the effects of In desorption. In this paper, we report on the impact of the quantum well growth temperature on the optical properties of InGaN/GaN multiple quantum wells designed to emit at 460 nm and 530 nm. It was found that for both sets of samples increasing the temperature at which the InGaN quantum well was grown, while maintaining the same indium composition, led to an increase in the internal quantum efficiency measured at 300 K. These increases in internal quantum efficiency are shown to be due reductions in the non-radiative recombination rate which we attribute to reductions in point defect incorporation.

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“…It is anticipated that this increase in the radiative recombination lifetime in green emitting samples leads to less efficient competition with non-radiative recombination pathways, resulting in the reduction in EQE for green LEDs. However it has been suggested that this increase in radiative recombination lifetime alone is not sufficient to explain the extent to which the EQE is reduced in green emitting devices [8,9], and that the effects of non-radiative recombination must also be increased.…”

mentioning

confidence: 99%

Effect of QW growth temperature on the optical properties of blue and green InGaN/GaN QW structures

Hammersley

Kappers

Massabuau

et al. 2016

Phys. Status Solidi C

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In this paper we report on the impact that the quantum well growth temperature has on the internal quantum efficiency and carrier recombination dynamics of two sets of InGaN/GaN multiple quantum well samples, designed to emit at 460 and 530 nm, in which the indium content of the quantum wells within each sample set was maintained. Measurements of the internal quantum efficiency of each sample set showed a systematic variation, with quantum wells grown at a higher temperature exhibiting higher internal quantum efficiency and this variation was preserved at all excitation power densities. By investigating the carrier dynamics at both 10 K and 300 K we were able to attribute this change in internal quantum efficiency to a decrease in the non‐radiative recombination rate as the QW growth temperature was increased which we attribute to a decrease in incorporation of the point defects. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Strain-induced defects as nonradiative recombination centers in green-emitting GaInN/GaN quantum well structures

Cited by 77 publications

References 17 publications

Current Components and Their Temperature Dependence of Green and Blue Light-Emitting Diodes: A Quantitative Comparison

Current Components and Their Temperature Dependence of Green and Blue Light-Emitting Diodes: A Quantitative Comparison

Effects of quantum well growth temperature on the recombination efficiency of InGaN/GaN multiple quantum wells that emit in the green and blue spectral regions

Effect of QW growth temperature on the optical properties of blue and green InGaN/GaN QW structures

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