Performance and polarization effects in (112¯2) long wavelength light emitting diodes grown on stress relaxed InGaN buffer layers

Koslow, Ingrid; Hardy, Matthew T.; Hsu, Po Shan; Dang, Po-Yuan; Wu, Feng; Романов, А. Е.; Wu, Yuh-Renn; Young, Erin C.; Nakamura, Shuji; Speck, James S.; DenBaars, Steven P.

doi:10.1063/1.4753949

Cited by 54 publications

(44 citation statements)

References 21 publications

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“…In recent, semipolar (nn01) InGaN/GaN ridge QWs (n = 1−3) [18] as well as the use of semipolar micropyramid LED arrays [19] approaches were reported. More recently, the use of microstructured multifacet QWs as active layers has also been reported with emission color tunable encompasses green to blue to achieve white LEDs [20], [21]. Among these semipolar facets, the advantages of {1101} planes are their thermodynamically stability under the InGaN growth conditions and highly uniformed QWs grown on these planes.…”

Section: Introductionmentioning

confidence: 98%

Improved Quantum Efficiency in Semipolar $(1\bar{1}01)$ InGaN/GaN Quantum Wells Grown on GaN Prepared by Lateral Epitaxial Overgrowth

Zhu

Zeng

Liu

et al. 2013

IEEE Trans. Electron Devices

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We investigated the comparative structural and optical properties of semipolar InGaN/GaN multiple quantum wells (MQWs) grown on the (1101) facet GaN/sapphire substrate by metal-organic chemical vapor deposition using lateral epitaxial overgrowth. The scanning electron microscopy (SEM), photoluminescence (PL), and temperature-varying time-resolved photoluminescence measurement were performed to investigate the structure and optical properties. The cross-sectional SEM image shows that the stripe triangular structure of the QW with semipolar (1101) planes is obtained as sidewall facets with the mask stripes aligned along the GaN a-axis. The structural and optical advantages of semipolar orientations were confirmed by a modurate shift of the PL peak energy, higher internal quantum efficiency, and lower radiative recombination lifetime than the MQWs on (0001) GaN grown by conventional methods. The results were obtained because of the reduced polarization fields in semipolar InGaN/GaN MQWs comparing with that in polar (0001) MQWs.Index Terms-InGaN/GaN multiple quantum wells, lateral epitaxial overgrowth, photoluminescence, semipolar.

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Section: Introductionmentioning

confidence: 98%

Improved Quantum Efficiency in Semipolar $(1\bar{1}01)$ InGaN/GaN Quantum Wells Grown on GaN Prepared by Lateral Epitaxial Overgrowth

Zhu

Zeng

Liu

et al. 2013

IEEE Trans. Electron Devices

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“…The reduction in charge separation leads to improved internal quantum efficiency and suppression in droop. Several methods for achieving InGaN QW with improved overlap design had been reported by using staggered or graded InGaN QW [23]- [30], type-II InGaN-based QW [31]- [33], delta-like QW [34]- [36], as well as the use of nonpolar/semipolar QWs [37], [38] and ternary substrate [39] approaches. The use of graded growth temperature profiling had also been reported for shaping the In-composition in the QW with improved overlap design, resulting in improved light output power and IQE of the LEDs [22]- [24].…”

Section: Introductionmentioning

confidence: 99%

Efficiency Droop Improvement in InGaN/GaN Light-Emitting Diodes by Graded-Composition Multiple Quantum Wells

et al. 2013

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InGaN/GaN light-emitting diodes (LEDs) with a graded-composition multiple quantum well (GQW) were designed not only to investigate the effect of polarization field on the efficiency droop in InGaN/GaN multiple quantum wells (MQWs) but to find out possible solutions to prevent or reduce the efficiency droop in GaN-based LEDs as well. Pulsed electroluminescence measurement, to avoid heating effects partly, revealed that the output intensity peak occurs at $ 280 A/cm 2 current density for the GQW structure, whereas for a conventional structure, it occurs at a much lower current density of $150 A/cm 2 . The relative quantum efficiency indicates that the efficiency droop in GQW LEDs was reduced effectively due to the reduction in polarization field in the active layer. In the test GQW structure with inverse indium composition variation direction, electrons escape from the active region, which is in company with rapid saturation of output power and decrease in efficiency observed at high current density. It indicates that at high current density, the electron leakage is obvious. These results suggest that the polarization field in the active layer and the consequent electron leakage are probably the main mechanism responsible for the efficiency droop at high current injection levels.Index Terms: Metal-organic chemical vapor deposition (MOCVD), InGaN/GaN multiple quantum well (MQW), electron leakage, efficiency droop.

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“…For semi-polar layers even smaller critical thicknesses have been reported. 10,11,20,21 Hence, the calculations in this paper rather indicate an upper limit.…”

mentioning

confidence: 99%

“…Such buffers have been used on semi-polar substrates, where the introduction of a tilt allows for effective relaxation and hence increases the critical thickness. 10,11 Fig . 3 investigates the effect of a relaxed InGaN buffer layer on a 40% InGaN QW.…”

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Wavelength limits for InGaN quantum wells on GaN

Pristovsek

2013

Applied Physics Letters

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The emission wavelength of coherently strained InGaN quantum wells (QW) is limited by the maximum thickness before relaxation starts. For high indium contents x>40% the resulting wavelength decreases because quantum confinement dominates. For low indium content x<40% the electron hole wave function overlap (and hence radiative emission) is strongly reduced with increasing QW thickness due to the quantum confined Stark effect and imposes another limit. This results in a maximum usable emission wavelength at around 600 nm for QWs with 40%-50% indium content. Relaxed InGaN buffer layers could help to push this further, especially on non- and semi-polar orientations.

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Performance and polarization effects in (112¯2) long wavelength light emitting diodes grown on stress relaxed InGaN buffer layers

Cited by 54 publications

References 21 publications

Improved Quantum Efficiency in Semipolar $(1\bar{1}01)$ InGaN/GaN Quantum Wells Grown on GaN Prepared by Lateral Epitaxial Overgrowth

Improved Quantum Efficiency in Semipolar $(1\bar{1}01)$ InGaN/GaN Quantum Wells Grown on GaN Prepared by Lateral Epitaxial Overgrowth

Efficiency Droop Improvement in InGaN/GaN Light-Emitting Diodes by Graded-Composition Multiple Quantum Wells

Wavelength limits for InGaN quantum wells on GaN

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