Effect of superlattice on light output power of InGaN‐based light‐emitting diodes fabricated on underlying GaN substrates with different dislocation densities

Sugimoto, Kazutaka; Denpo, Yusho; Okada, Narihito; Tadatomo, Kazuyuki

doi:10.1002/pssc.201510203

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…The high efficiency of standard c -planar LEDs corresponds to extensive research efforts during more than two decades. Among all strategies to raise the efficiency, the use of ULs can exhibit impressive enhancement of efficiency in InGaN/GaN MQW structures by exploiting different types of buffer layers in InGaN/GaN structures such as short-period InGaN/GaN superlattices, , Si-doped (In)GaN prelayers, and InGaN UL with low In content. − A recent investigation about the role of InGaN UL to increase the InGaN/GaN QW efficiency reveals that an optimized thickness of 55 nm with around 3% indium content significantly improves the EQE by 3.5 times while at room temperature, the QW effective lifetime increases from 170 ps (no UL present) to 20 ns (with UL), indicating a low nonradiative (NR) recombination rate . According to the proposed mechanism, the NR centers correspond to the GaN surface point defects created by the high-temperature growth of GaN prior to QW.…”

Section: Introductionmentioning

confidence: 99%

Role of Underlayer for Efficient Core–Shell InGaN QWs Grown on m-plane GaN Wire Sidewalls

Kapoor

Finot

Grenier

et al. 2020

ACS Appl. Mater. Interfaces

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Different types of buffer layers like InGaN underlayer (UL) and InGaN/GaN superlattices are now well-known to significantly improve the efficiency of c-plane InGaN/GaN based light emitting diodes (LEDs). The present work investigates the role of two different kinds of pregrowth layers (low In-content InGaN UL and GaN UL namely "GaN spacer") on the emission of core-shell m-plane InGaN/GaN single quantum well (QW) grown around Si-doped !̅-GaN microwires obtained by silane-assisted MOVPE. According to photo-and cathodoluminescence measurements performed at room temperature, an improved efficiency of light emission at 435 nm with internal quantum efficiency > 15 % has been achieved by adding a GaN spacer prior to the growth of QW. As revealed by scanning transmission electron microscopy, an ultra-thin residual layer containing Si located at the wire sidewall surfaces favors the formation of highdensity of extended defects nucleated at the first InGaN QW. This contaminated residual incorporation is buried by the growth of GaN spacer and avoids the structural defect formation, therefore explaining the improved optical efficiency. No further improvement is observed by adding the InGaN UL to the structure, which is confirmed by comparable values of the effective carrier lifetime estimated from time-resolved (TR) experiments. Contrary to the case of planar cplane QW where the improved efficiency is attributed to a strong decrease of point defects, the addition of an InGaN UL seem to have no influence in the case of radial m-plane QW.

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Section: Introductionmentioning

confidence: 99%

Role of Underlayer for Efficient Core–Shell InGaN QWs Grown on m-plane GaN Wire Sidewalls

Kapoor

Finot

Grenier

et al. 2020

ACS Appl. Mater. Interfaces

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“…Recently, V‐pits have been found to have a positive effect on the InGaN PL properties . Several explanations were suggested, one of which is strain relaxation and reduction in QW region.…”

Section: Resultsmentioning

confidence: 99%

InGaN/GaN Structures: Effect of the Quantum Well Number on the Cathodoluminescent Properties

Hospodková

Hubáček

Oswald

et al. 2017

Physica Status Solidi (b)

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In this work we compare luminescence results obtained on InGaN/GaN multiple quantum well (QW) structures with 10 and 30 QWs. The aim is to increase the intensity of faster blue QW emission and decrease the luminescence of the QW defect band, showing a slower luminescence decay time, which is undesired for fast scintillator applications. We demonstrate that increasing the number of InGaN QWs is an efficient method to reach this goal. The luminescence improvement of the sample with higher number of QWs is explained by the influence of the increased size of V‐pits with increased QW number. Thinner QWs on the side wall of V‐pits serve as barriers which separate carriers from dislocations penetrating through the V‐pit centre, supressing thus the non‐radiative and radiative recombination on defects. Based on cathodoluminescence (CL) results, the scintillator structure design is discussed. Scintillator structures with higher number of QWs can take advantage of both, improved luminescence efficiency and thicker active region.

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Influence of GaN buffer layer under InGaN/GaN MQWs on luminescent properties

Dominec

Hospodková

Hubáček

et al. 2019

Journal of Crystal Growth

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Effect of superlattice on light output power of InGaN‐based light‐emitting diodes fabricated on underlying GaN substrates with different dislocation densities

Cited by 5 publications

References 16 publications

Role of Underlayer for Efficient Core–Shell InGaN QWs Grown on m-plane GaN Wire Sidewalls

Role of Underlayer for Efficient Core–Shell InGaN QWs Grown on m-plane GaN Wire Sidewalls

InGaN/GaN Structures: Effect of the Quantum Well Number on the Cathodoluminescent Properties

Influence of GaN buffer layer under InGaN/GaN MQWs on luminescent properties

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