Burying non-radiative defects in InGaN underlayer to increase InGaN/GaN quantum well efficiency

Haller, Camille; Carlin, J.-F.; Jacopin, Gwenolé; Martin, D.; Butté, R.; Grandjean, N.

doi:10.1063/1.5007616

Cited by 111 publications

(84 citation statements)

References 21 publications

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“…The insertion of an InGaN or InGaN/GaN superlattice (SL) underlayer in the epi-structure is known to strongly improve the efficiency of GaN-based LEDs. The inclusion of such a layer has been extensively reported in the literature, and several mechanisms have been proposed to explain the improvement in LED efficiency 24 – 33 . Leem et al .…”

Section: Introductionmentioning

confidence: 99%

The effect of nanometre-scale V-pits on electronic and optical properties and efficiency droop of GaN-based green light-emitting diodes

Zhou

Liu

Yan

et al. 2018

Sci Rep

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The development of efficient green light-emitting diodes (LEDs) is of paramount importance for the realization of colour-mixing white LEDs with a high luminous efficiency. While the insertion of an InGaN/GaN superlattice (SL) with a lower In content before the growth of InGaN/GaN multiple quantum wells (MQWs) is known to increase the efficiency of LEDs, the actual mechanism is still debated. We therefore conduct a systematic study and investigate the different mechanisms for this system. Through cathodoluminescence and Raman measurements, we clearly demonstrate that the potential barrier formed by the V-pit during the low-temperature growth of an InGaN/GaN SL dramatically increases the internal quantum efficiency (IQE) of InGaN quantum wells (QWs) by suppressing non-radiative recombination at threading dislocations (TDs). We find that the V-pit potential barrier height depends on the V-pit diameter, which plays an important role in determining the quantum efficiency, forward voltage and efficiency droop of green LEDs. Furthermore, our study reveals that the low-temperature GaN can act as an alternative to an InGaN/GaN SL structure for promoting the formation of V-pits. Our findings suggest the potential of implementing optimized V-pits embedded in an InGaN/GaN SL or low-temperature GaN structure as a beneficial underlying layer for the realization of highly efficient green LEDs.

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Section: Introductionmentioning

confidence: 99%

The effect of nanometre-scale V-pits on electronic and optical properties and efficiency droop of GaN-based green light-emitting diodes

Zhou

Liu

Yan

et al. 2018

Sci Rep

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“…We study samples with 4 nm-thick single-QWs within p-i-n regions, grown on c-plane bulk GaN substrates by MOCVD; these samples include an InGaN underlayer (UL) beneath the p-i-n region, which improves material quality [10][11][12]. Importantly, the QW is placed at the center of the intrinsic region to avoid modulation-doping, which would alter the recombination dynamics [13].…”

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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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“…Usually this occurs because of the more effective competition with non-radiative processes associated with defects of impurities. However, it should be noted that it has also been proposed that the addition of ULs to a structure leads to a reduced impurity incorporation at interfaces [ 18 ] similar to observations first made [ 19 ] in GaAs/AlGaAs heterostructures.…”

Section: Introductionmentioning

confidence: 64%

Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells

et al. 2018

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In this paper we report on the optical properties of a series of InGaN polar quantum well structures where the number of wells was 1, 3, 5, 7, 10 and 15 and which were grown with the inclusion of an InGaN Si-doped underlayer. When the number of quantum wells is low then the room temperature internal quantum efficiency can be dominated by thermionic emission from the wells. This can occur because the radiative recombination rate in InGaN polar quantum wells can be low due to the built-in electric field across the quantum well which allows the thermionic emission process to compete effectively at room temperature limiting the internal quantum efficiency. In the structures that we discuss here, the radiative recombination rate is increased due to the effects of the Si-doped underlayer which reduces the electric field across the quantum wells. This results in the effect of thermionic emission being largely eliminated to such an extent that the internal quantum efficiency at room temperature is independent of the number of quantum wells.

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Burying non-radiative defects in InGaN underlayer to increase InGaN/GaN quantum well efficiency

Cited by 111 publications

References 21 publications

The effect of nanometre-scale V-pits on electronic and optical properties and efficiency droop of GaN-based green light-emitting diodes

The effect of nanometre-scale V-pits on electronic and optical properties and efficiency droop of GaN-based green light-emitting diodes

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

Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells

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