A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array

Zhan, Jing; Chen, Zhizhong; Deng, Chuhan; Jiao, Fei; Xi, Xin; Chen, Yiyong; Nie, Jingxin; Pan, Zuojian; Zhang, Haodong; Dong, Boyan; Kang, Xiaoning; Wang, Qi; Tong, Yuzhen; Zhang, Guoyi; Shen, Bo

doi:10.3390/nano12213880

Cited by 3 publications

(3 citation statements)

References 61 publications

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“…Flocculent-like green luminescence and dot-like red luminescence can be seen in figure 2(b) before annealing. The flocculent-like green emission arises from the continuous regions apart from the defects, such as SMBs in trench defects [22] and In-rich clusters in green MQWs [29]. The dot-like red emission originates from the red QWs inside trenches, as confirmed by figures 1(b) and (c).…”

Section: Resultssupporting

confidence: 59%

Thermally stable radiative recombination centers within trench structures of red multi-quantum wells

Pan,

Yang,

Chen

et al. 2024

J. Phys. D: Appl. Phys.

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High-Indium (In)-content multi-quantum wells (MQWs) are generally thermally unstable due to poor crystal quality resulting from low-temperature growth. In this study, red emission was achieved by modulating trench structures using dual-color MQW structures. Impressively, the red MQWs inside deep trenches showed excellent thermal stability despite being grown at low temperatures. After high-temperature annealing at 950 °C for 30 minutes, the photoluminescence (PL) intensity of red MQWs exhibited a significant reduction of 91.9% outside trenches, while it dropped by only 9.3% inside trenches, as confirmed by confocal PL mapping. Transmission electron microscopy results show that massive In-rich phases and stacking faults appeared in the MQWs outside trenches after annealing. By contrast, the red MQWs inside deep trenches remained intact in lattice arrangement without being significantly damaged. The superior thermal stability of red MQWs inside deep trenches was mainly attributed to the low-defect-density epitaxy of InGaN layers in strain-relaxed states.

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Section: Resultssupporting

confidence: 59%

Thermally stable radiative recombination centers within trench structures of red multi-quantum wells

Pan,

Yang,

Chen

et al. 2024

J. Phys. D: Appl. Phys.

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“…Meanwhile, the blocking of the trench prevents the red MQWs inside the trench from being affected by defects in the surrounding region, similar to defect shielding by nanorods. [ 56 ] As a result, the red MQWs inside the trench would shield the defects in both the growth direction and in‐plane dimensions, effectively reducing their nonradiative recombination. Second, the trench defects can relax the compressive strain, effectively weakening the polarization electric field of red MQWs inside the trench loops, as demonstrated by confocal PL results.…”

Section: Resultsmentioning

confidence: 99%

Efficient InGaN‐Based Red Light‐Emitting Diodes by Modulating Trench Defects

Pan,

Chen,

Zhang

et al. 2024

Adv Funct Materials

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Trench defects in multi‐quantum wells (MQWs) have been considered as flawed structures that severely degraded the internal quantum efficiency (IQE) of light‐emitting diodes (LEDs) in the past. In this research, trench defects are innovatively utilized to enhance the efficiency of red InGaN LEDs. Specifically, dual‐color MQWs structures are applied to modulate trench defects. The upper red MQWs, grown on top of green MQWs with a high density of trench defects, exhibit a significant wavelength redshift of 68 nm and ≈ 6‐fold luminescence enhancement compared to those without intentionally introduced trench defects. Red InGaN LEDs with an IQE of 16.4% are achieved with this epitaxy growth strategy. Such wavelength redshift is attributed to the more indium incorporation due to the strain relaxation effect of trench defects. Moreover, the luminescence enhancement originates from the strong emission of the red MQWs inside trench defects, mainly attributed to strain relaxation and defect shielding by the wide and deep trenches. Achieving red emission by modulating trench defects is simple and reproducible without requiring additional substrate designs, which provides a novel way toward high‐efficiency red InGaN LEDs.

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“…The development of GaN-based nanorod LEDs is expected to provide a significant advancement in display technology, offering unparalleled brightness, resolution, and miniaturization. The nanorod LED structure is expected to exhibit a high crystallinity with reduced stacking faults, threading dislocation densities, and piezoelectric polarization [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Investigation into the Effects of Cross-Sectional Shape and Size on the Light-Extraction Efficiency of GaN-Based Blue Nanorod Light-Emitting Diode Structures

Lee,

Ryu

2024

Crystals

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We investigated the effect of cross-sectional shape and size on the light-extraction efficiency (LEE) of GaN-based blue nanorod light-emitting diode (LED) structures using numerical simulations based on finite-difference time-domain methods. For accurate determination, the LEE and far-field pattern (FFP) were evaluated by averaging them over emission spectra, polarization, and source positions inside the nanorod. The LEE decreased as rod size increased, owing to the nanorods’ increased ratio of cross-sectional area to sidewall area. We compared circular, square, triangular, and hexagonal cross-sectional shapes in this study. To date, nanorod LEDs with circular cross sections have been mainly demonstrated experimentally. However, circular shapes were found to show the lowest LEE, which is attributed to the coupling with whispering-gallery modes. For the total emission of the nanorod, the triangular cross section exhibited the highest LEE. When the angular dependence of the LEE was calculated using the FFP simulation results, the triangular and hexagonal shapes showed relatively high LEEs for direction emission. The simulation results presented in this study are expected to be useful in designing high-efficiency nanorod LED structures with optimum nanorod shape and dimensions.

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A Novel Way to Fill Green Gap of GaN-Based LEDs by Pinning Defects in Nanorod Array

Cited by 3 publications

References 61 publications

Thermally stable radiative recombination centers within trench structures of red multi-quantum wells

Thermally stable radiative recombination centers within trench structures of red multi-quantum wells

Efficient InGaN‐Based Red Light‐Emitting Diodes by Modulating Trench Defects

Investigation into the Effects of Cross-Sectional Shape and Size on the Light-Extraction Efficiency of GaN-Based Blue Nanorod Light-Emitting Diode Structures

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