Efficient emission of InGaN-based light-emitting diodes: toward orange and red

Zhang, Shengnan; Zhang, Jianli; Gao, Jiang-Dong; Wang, Xiaolan; Chang, Zheng; Meng, Zhongyan; Wu, Xiaoming; Xu, Ling; Ding, Jie; Quan, Zhi; Jiang, Fengyi

doi:10.1364/prj.402555

Cited by 134 publications

(100 citation statements)

References 37 publications

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“…Because the QCSE and the band filling effect were respectively originated from the in-plane strain and In fluctuation in InGaN QWs, the strain relaxation and the improvement of the InGaN crystal quality were vital for suppressing this large blue-shift. The FWHM at the current density below 20 A/cm 2 remained 50-51 nm, which was comparable to the best values of other InGaN orange and red LEDs [15,27]. However, the FWHM increased to around 56 nm with a current density up to 100 A/cm 2 .…”

Section: Resultssupporting

confidence: 81%

“…Recently, 6 × 6 µm 2 size 632-nm InGaN µLEDs on porous GaN were demonstrated to have an on-wafer EQE of 0.2%, which was the first reported value for red µLEDs with the dimension < 10 µm [14]. Besides, orange/red InGaN LEDs could realize high efficiency on silicon substrates [15] because the tensile strain of the GaN on silicon during growth was favorable for In incorporation [11]. Our group chose to adjust the thickness of the GaN on sapphire substrates to realize highly efficient InGaN red LEDs [16].…”

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confidence: 99%

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606-nm InGaN Amber Micro-Light-Emitting Diodes With an On-Wafer External Quantum Efficiency of 0.56%

Zhuang

Iida

Ohkawa

2021

IEEE Electron Device Lett.

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We demonstrated amber InGaN 47 × 47 µm 2 micro-light-emitting diodes (µLEDs) with the peak wavelength of 606 nm and full-width at maximum (FWHM) of 50 nm at 20 A/cm 2 . The amber µLEDs exhibited a 33-nm blue-shift of the peak wavelength and obtain broader FWHMs to approximately 56 nm at 5 to 100 A/cm 2 . The peak on-wafer external quantum efficiency was 0.56% at 20 A/cm 2 . The characteristic temperature was 50-80 K at 20 to 60 A/cm 2 but increased to 120-140 K at 80 to 100 A/cm 2 . The strong increase in the characteristic temperature from 60 to 80 A/cm 2 could mainly be attributed to the saturation of the Shockley-Read-Hall non-radiative recombination at high current densities. Index Terms-InGaN, amber micro-light-emitting diode, on-wafer external quantum efficiency, characteristic temperature I. INTRODUCTIONUE to their high brightness levels, long lifetime, large modulation bandwidth, and small form factors, InGaN-based micro-light-emitting diodes (µLEDs) have achieved expanding interests in many newly-emerging applications such as micro-displays in wearable and smart electronics, visible light communication, and biomedical sensors [1,2]. Although InGaN blue and green LEDs have been commercialized owing to their mature technology and This work was financially supported by King Abdullah University of Science and Technology (KAUST) (BAS/1/1676-01-01). The fabrication processes were supported by Nanofabrication Core Labs in KAUST.

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Section: Resultssupporting

confidence: 81%

mentioning

confidence: 99%

606-nm InGaN Amber Micro-Light-Emitting Diodes With an On-Wafer External Quantum Efficiency of 0.56%

Zhuang

Iida

Ohkawa

2021

IEEE Electron Device Lett.

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“…By utilizing the benefits of V-pit to screen dislocations and enhance hole injection, Zhang and his co-works have created efficient InGaN-based LEDs with peak efficiency up to 24.0% at 0.8 A/cm 2 . However, the LED chips reported by Zhang et al is still limited to of tranditional size (1 mm × 1 mm), which is much larger than that of micro-LED [ 25 ]. Moreover, many works have reported that the internal quantum efficiency (IQE) and EQE of micro-LEDs decrease as the chip size is reduced [ 26 – 28 ].…”

Section: Introductionmentioning

confidence: 99%

Designs of InGaN Micro-LED Structure for Improving Quantum Efficiency at Low Current Density

Huang

et al. 2021

Nanoscale Res Lett

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Here we report a comprehensive numerical study for the operating behavior and physical mechanism of nitride micro-light-emitting-diode (micro-LED) at low current density. Analysis for the polarization effect shows that micro-LED suffers a severer quantum-confined Stark effect at low current density, which poses challenges for improving efficiency and realizing stable full-color emission. Carrier transport and matching are analyzed to determine the best operating conditions and optimize the structure design of micro-LED at low current density. It is shown that less quantum well number in the active region enhances carrier matching and radiative recombination rate, leading to higher quantum efficiency and output power. Effectiveness of the electron blocking layer (EBL) for micro-LED is discussed. By removing the EBL, the electron confinement and hole injection are found to be improved simultaneously, hence the emission of micro-LED is enhanced significantly at low current density. The recombination processes regarding Auger and Shockley–Read–Hall are investigated, and the sensitivity to defect is highlighted for micro-LED at low current density.Synopsis: The polarization-induced QCSE, the carrier transport and matching, and recombination processes of InGaN micro-LEDs operating at low current density are numerically investigated. Based on the understanding of these device behaviors and mechanisms, specifically designed epitaxial structures including two QWs, highly doped or without EBL and p-GaN with high hole concentration for the efficient micro-LED emissive display are proposed. The sensitivity to defect density is also highlighted for micro-LED.

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“…To our knowledge, this on-wafer EQE is the highest reported value for InGaN red µLEDs. Recently, a high wall-plug efficiency (WPE) of 16.8% at 621 nm was obtained at 0.8 A/cm 2 for 1×1 mm 2 InGaN-based LEDs [15]. This WPE value was the highest for standard InGaN red LEDs.…”

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confidence: 99%

Investigation of InGaN-based red/green micro-light-emitting diodes

2021

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We investigated the performance of InGaN-based red/green micro-light-emitting diodes (µLEDs) ranging from 98×98 to 17×17 µm 2 . The average forward voltage at 10 A/cm 2 was independent of the dimension of µLEDs. Red µLEDs exhibited a larger blue-shift of the peak wavelength (~35 nm) and broader full-width at half maximum (≥50 nm) at 2 to 50 A/cm 2 compared to green µLEDs. We demonstrated that 47×47 µm 2 red µLEDs had an on-wafer external quantum efficiency of 0.36% at the peak wavelength of 626 nm, close to the red primary color defined in the recommendation 2020 standard.

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Efficient emission of InGaN-based light-emitting diodes: toward orange and red

Cited by 134 publications

References 37 publications

606-nm InGaN Amber Micro-Light-Emitting Diodes With an On-Wafer External Quantum Efficiency of 0.56%

606-nm InGaN Amber Micro-Light-Emitting Diodes With an On-Wafer External Quantum Efficiency of 0.56%

Designs of InGaN Micro-LED Structure for Improving Quantum Efficiency at Low Current Density

Investigation of InGaN-based red/green micro-light-emitting diodes

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