Study of green light-emitting diodes grown on semipolar (11–22) GaN/m-sapphire with different crystal qualities

Dong-Sub, Oh，; Jang, Jongjin; Nam, Okhyun; Song, Kwang Hyun; Lee, Sung‐Nam

doi:10.1016/j.jcrysgro.2011.01.046

Cited by 24 publications

(11 citation statements)

References 15 publications

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“…Figure 5 shows the

m 2 AFM 3D microtopographic images of the (11

2) GaN superlattice templates. A typical crosshatch surface morphology that showed a characteristic undulating morphology with hills and valleys parallel to the [

23] direction for the (11

2) GaN superlattice templates could be remarkably observed, which was directly correlated with the presence of an interfacial misfit dislocation [ 37 , 38 ]. As the InGaN thickness increased in the superlattice structures, the strain energy increased and an additional misfit dislocation formed at the heterogenous interface to relieve the resulting strain in the remarkable crosshatch surface morphology.…”

Section: Resultsmentioning

confidence: 99%

Anisotropic Strain Relaxation in Semipolar (112¯2) InGaN/GaN Superlattice Relaxed Templates

Wang

Chai

et al. 2022

Nanomaterials

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Semipolar (112¯2) InGaN/GaN superlattice templates with different periodical InGaN layer thicknesses were grown on m-plane sapphire substrates using metal-organic chemical vapor deposition (MOCVD). The strain in the superlattice layers, the relaxation mechanism and the influence of the strain relaxation on the semipolar superlattice template were explored. The results demonstrated that the strain in the (112¯2) InGaN/GaN superlattice templates was anisotropic and increased with increasing InGaN thickness. The strain relaxation in the InGaN/GaN superlattice templates was related to the formation of one-dimension misfit dislocation arrays in the superlattice structure, which caused tilts in the superlattice layer. Whereas, the rate of increase of the strain became slower with increasing InGaN thickness and new misfit dislocations emerged, which damaged the quality of the superlattice relaxed templates. The strain relaxation in the superlattice structure improved the surface microtopography and increased the incorporation of indium in the InGaN epitaxial layers.

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“…Figure 5 shows the

m 2 AFM 3D microtopographic images of the (11

2) GaN superlattice templates. A typical crosshatch surface morphology that showed a characteristic undulating morphology with hills and valleys parallel to the [

23] direction for the (11

Section: Resultsmentioning

confidence: 99%

Anisotropic Strain Relaxation in Semipolar (112¯2) InGaN/GaN Superlattice Relaxed Templates

Wang

Chai

et al. 2022

Nanomaterials

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“…Several solutions have been proposed to enhance the efficiency of green LEDs including nanopatterned sapphire substrate 18 , staggered InGaN QW 19,20 , non- and semi-polar QWs 21–23 , lattice-matched AlGaInN barrier 24 , and AlGaN or AlInN interlayers 25–28 . An in-situ low-temperature GaN (LT-GaN) or AlN nucleation layer (NL) between the high-temperature GaN epilayers and substrate is generally introduced to reduce defect density in GaN film 29,30 .…”

Section: Introductionmentioning

confidence: 99%

Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer

Zhou

Wan

et al. 2019

Sci Rep

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Here we demonstrate high-brightness InGaN/GaN green light emitting diodes (LEDs) with in-situ low-temperature GaN (LT-GaN) nucleation layer (NL) and ex-situ sputtered AlN NL on 4-inch patterned sapphire substrate. Compared to green LEDs on LT-GaN (19 nm)/sapphire template, green LEDs on sputtered AlN (19 nm)/template has better crystal quality while larger in-plane compressive strain. As a result, the external quantum efficiency (EQE) of green LEDs on sputtered AlN (19 nm)/sapphire template is lower than that of green LEDs on LT-GaN (19 nm)/sapphire template due to strain-induced quantum-confined Stark effect (QCSE). We show that the in-plane compressive strain of green LEDs on sputtered AlN/sapphire templates can be manipulated by changing thickness of the sputtered AlN NL. As the thickness of sputtered AlN NL changes from 19 nm to 40 nm, the green LED on sputtered AlN (33 nm)/sapphire template exhibits the lowest in-plane compressive stress and the highest EQE. At 20 A/cm 2 , the EQE of 526 nm green LEDs on sputtered AlN (33 nm)/sapphire template is 36.4%, about 6.1% larger than that of the green LED on LT-GaN (19 nm)/sapphire template. Our experimental data suggest that high-efficiency green LEDs can be realized by growing InGaN/GaN multiple quantum wells (MQWs) on sputtered AlN/sapphire template with reduced in-plane compressive strain and improved crystal quality.

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“…Nevertheless, semipolar GaN layers grown on foreign substrates suffer from high densities of basal stacking faults (BSFs) and threading dislocations (TDs), leading to low efficiency devices . Efforts have been focused on defect management to improve the crystal quality of semipolar GaN materials grown on foreign ones to improve the device performance. − To date, a few papers have been reported on semipolar LEDs with long emission wavelength on sapphire substrates, and those LEDs still exhibit low output power and reduced external quantum efficiency (EQE). − …”

Section: Introductionmentioning

confidence: 99%

Efficient Semipolar (11–22) 550 nm Yellow/Green InGaN Light-Emitting Diodes on Low Defect Density (11–22) GaN/Sapphire Templates

Khoury

Bonef

et al. 2017

ACS Appl. Mater. Interfaces

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We demonstrate efficient semipolar (11-22) 550 nm yellow/green InGaN light-emitting diodes (LEDs) with InGaN barriers on low defect density (11-22) GaN/patterned sapphire templates. The InGaN barriers were clearly identified, and no InGaN clusters were observed by atom probe tomography measurements. The semipolar (11-22) 550 nm InGaN LEDs (0.1 mm size) show an output power of 2.4 mW at 100 mA and a peak external quantum efficiency of 1.3% with a low efficiency drop. In addition, the LEDs exhibit a small blue-shift of only 11 nm as injection current increases from 5 to 100 mA. These results suggest the potential to produce high efficiency semipolar InGaN LEDs with long emission wavelength on large-area sapphire substrates with economical feasibility.

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Study of green light-emitting diodes grown on semipolar (11–22) GaN/m-sapphire with different crystal qualities

Cited by 24 publications

References 15 publications

Anisotropic Strain Relaxation in Semipolar (112¯2) InGaN/GaN Superlattice Relaxed Templates

Anisotropic Strain Relaxation in Semipolar (112¯2) InGaN/GaN Superlattice Relaxed Templates

Effect of strain relaxation on performance of InGaN/GaN green LEDs grown on 4-inch sapphire substrate with sputtered AlN nucleation layer

Efficient Semipolar (11–22) 550 nm Yellow/Green InGaN Light-Emitting Diodes on Low Defect Density (11–22) GaN/Sapphire Templates

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