High luminous efficacy green light-emitting diodes with AlGaN cap layer

Alhassan, Abdullah I.; Farrell, Robert M.; SaifAddin, Burhan K.; Mughal, Asad J.; Wu, Feng; DenBaars, Steven P.; Nakamura, Shuji; Speck, James S.

doi:10.1364/oe.24.017868

Cited by 82 publications

(46 citation statements)

References 21 publications

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“…Those EQE values are somewhat lower than that of recently reported maximum values 93940. Internal quantum efficiencies of the UV (43.0%), blue (64.5%), and green (12.7%) LEDs, even though these are lower than reported maximum values414243, are almost not changed due to significantly small hole depth of 40 nm. Therefore, we can conclude that the increases of EQEs are induced by enhanced LEE From the L–I–V measurements, we determined that the enhancement in the light output power of the LEDs with PHPs is sensitive to the emission wavelength and a small depth of holes significantly affects the light output power of the LEDs, with only limited slight changes in the electrical properties.…”

Section: Resultscontrasting

confidence: 65%

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

Jeong

Salas‐Montiel

Lerondel

et al. 2017

Sci Rep

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In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results.

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Section: Resultscontrasting

confidence: 65%

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

Jeong

Salas‐Montiel

Lerondel

et al. 2017

Sci Rep

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“…One more problem limiting the performance of InGaN-based LEDs is the so called "green gap", i.e., substantial EQE decline with the emission wavelength from blue (~430-440 nm) towards the green/yellow (~500-600 nm) spectral range. Indeed, the maximum EQE values of LEDs operating in the green,~40-50% [7,8], and yellow,~20% [9], spectral ranges are remarkably lower than that in the violet/blue one, which cannot be attributed to insufficient light extraction from the LED dice [10]. In addition, a remarkable increase in the threshold current density and decrease in the wall-plug efficiency of InGaN-based laser diodes is also observed in the same spectral range [11,12].…”

Section: Introductionmentioning

confidence: 99%

Effect of Carrier Localization on Recombination Processes and Efficiency of InGaN-Based LEDs Operating in the “Green Gap”

Karpov¹

2018

Applied Sciences

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A semi-empirical model of carrier recombination accounting for hole localization by composition fluctuations in InGaN alloys is extended to polar and nonpolar quantum-well structures. The model provides quantitative agreement with available data on wavelength-dependent radiative and Auger recombination coefficients in polar LEDs. Comparison of calculated internal quantum efficiencies of polar and nonpolar LEDs enables an assessment of the roles of carrier localization, quantum-confined Stark effect, and native material properties for the efficiency decline in the "green gap".

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“…One approach for higher efficiency longer wavelength InGaN LEDs that has produced record efficiencies at green gap wavelengths is the use of AlGaN interlayers in the multiple quantum well (MQW) active layer. [87,96,[121][122][123][124][125][126][127] This is most interesting in the green and red because of demonstrated record external quantum efficiencies of 25% at 550 nm [125] and 2.5% at 608 nm. The AlGaN interlayer (IL) is grown on top of the InGaN quantum well as shown in Figure 5a.…”

Section: Solutions For Higher Efficiencies Of Green and Red Emittersmentioning

confidence: 99%

III‐Nitride Micro‐LEDs for Efficient Emissive Displays

Wierer

Tansu

2019

Laser & Photonics Reviews

119

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Emissive displays based on light‐emitting diodes (LEDs), with high pixel density, luminance, efficiency, and large color gamut, are of great interest for applications such as watches, phones, and virtual displays. The high pixel density requirements of some emissive displays require a particular class of LEDs that are sub‐20‐micrometers in length, called micro‐LEDs. While state‐of‐the‐art emissive displays incorporate organic LEDs, an alternative is inorganic III‐nitride LEDs with potential reliability and efficiency benefits. Here we explore the performance, challenges, and prospective outcomes for III‐nitride micro‐LEDs to produce efficient emissive displays and provide insight to advance this technology. Calculations are performed to determine the operating points for the micro‐LEDs and the efficiency of the overall emissive display. It is shown that III‐nitride micro‐LEDs suffer from some of the same problems as their larger‐sized solid‐state lighting LED cousins; however, the operating conditions of micro‐LEDs can result in different challenges and research efforts. These challenges include improving efficiency at low current densities; improving the efficiency of longer wavelength (green and red) LEDs; and creating device designs that can overcome low coupling efficiency, high surface recombination, and display assembly difficulties.

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High luminous efficacy green light-emitting diodes with AlGaN cap layer

Cited by 82 publications

References 21 publications

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

Effect of Carrier Localization on Recombination Processes and Efficiency of InGaN-Based LEDs Operating in the “Green Gap”

III‐Nitride Micro‐LEDs for Efficient Emissive Displays

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