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, Simon; Kappers, Menno J.; Massabuau, Fabien; Sahonta, S.‐L.; Dawson, P.; Oliver, Rachel A.; Humphreys, C. J.

doi:10.1063/1.4932200

Cited by 65 publications

(59 citation statements)

References 38 publications

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“…These figures are compatible with the observation that InGaN/GaN QWs with the dislocation densities as high as 5 Â 10 8 cm À2 can exhibit high photoluminescence IQE at room temperature. This argument can only be regarded as approximate as the density of point defects can also play a role 60 in determining diffusion lengths and hence the IQE. As for nonpolar structures, it can be argued that the carrier localisation may not play as dominant role in determining the room temperature IQE as the radiative lifetime itself is so much shorter than that of polar QWs.…”

Section: Discussionmentioning

confidence: 99%

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Dawson

Schulz²,

Oliver

et al. 2016

Journal of Applied Physics

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In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.

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Section: Discussionmentioning

confidence: 99%

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Dawson

Schulz²,

Oliver

et al. 2016

Journal of Applied Physics

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“…Estimation of the (0001)InGaN/GaN critical thickness shows that it only becomes comparable with typical QW widths in the green/yellow spectral range [14]. Point defect generation defect generation and parasitic impurity incorporation are also expected to be enhanced at high InN fractions because of the lower growth temperatures normally used for increasing the indium content in InGaN QWs [15].…”

Section: Introductionmentioning

confidence: 99%

Effect of Carrier Localization on Recombination Processes and Efficiency of InGaN-Based LEDs Operating in the “Green Gap”

Karpov¹

2018

Applied Sciences

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A semi-empirical model of carrier recombination accounting for hole localization by composition fluctuations in InGaN alloys is extended to polar and nonpolar quantum-well structures. The model provides quantitative agreement with available data on wavelength-dependent radiative and Auger recombination coefficients in polar LEDs. Comparison of calculated internal quantum efficiencies of polar and nonpolar LEDs enables an assessment of the roles of carrier localization, quantum-confined Stark effect, and native material properties for the efficiency decline in the "green gap".

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“…Various explanations have been offered for the green gap. It has been proposed that high-In quantum wells (QWs) suffer from an increase in point defects [5,6] -however this should only impact low-current recombinations, whereas the green gap occurs at all currents. Other tentative explanations include an increase in electron-hole separation (leading to weaker radiative recombinations), due to increasing polarization fields and in-plane carrier localization [7][8][9].…”

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confidence: 99%

Quantum Efficiency of III-Nitride Emitters: Evidence for Defect-Assisted Nonradiative Recombination and its Effect on the Green Gap

et al. 2019

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Carrier lifetime measurements reveal that, contrary to common expectations, the high-current non-radiative recombination (droop) in III-Nitride light emitters is comprised of two contributions which scale with the cube of the carrier density: an intrinsic recombination -most likely standard Auger scattering-and an extrinsic recombination which is proportional to the density of point defects. This second droop mechanism, which hasn't previously been observed, may be caused by an impurity-assisted Auger process. Further, it is shown that longer-wavelength emitters suffer from higher point defect recombinations, in turn causing an increase in the extrinsic droop process. It is proposed that this effect leads to the green gap, and that point defect reduction is a strategy to both vanquish the green gap and more generally improve quantum efficiency at high current.

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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

Cited by 65 publications

References 38 publications

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Effect of Carrier Localization on Recombination Processes and Efficiency of InGaN-Based LEDs Operating in the “Green Gap”

Quantum Efficiency of III-Nitride Emitters: Evidence for Defect-Assisted Nonradiative Recombination and its Effect on the Green Gap

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