Improving the Brightness and Reliability of InGaN/GaN Near Ultraviolet Light-Emitting Diodes by Controlling the Morphology of the GaN Buffer Layer

Tsai, Sheng Chieh; Fang, Hongxia; Lü, Cheng; Lai, Yu-Cheng; Liu, C.-P.

doi:10.1109/jdt.2016.2535185

Cited by 5 publications

(2 citation statements)

References 25 publications

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“…Heterojunctions are composed of two semiconductors with different band gap sizes. The semiconductor with the larger band gap is used as the barrier, whereas that with the smaller band gap is used as the active region [12][13][14]. Because of the barrier, carriers at the heterojunction are effectively confined at the active region with smaller band gaps, thereby facilitating effective recombination of electron-hole pairs.…”

Section: Introductionmentioning

confidence: 99%

“…The QWs involve embedding a smaller band gap between two larger band gaps, which form barriers to effectively confine carriers within QWs and reduce carrier overflow, thereby improving the carrier concentration, increasing the radiant recombination efficiency, and improving the internal quantum efficiency. This structure is called the QW, which is the active region structure adopted by most efficient LEDs [14][15][16][17][18]. During the process of growing heterostructures, stress accumulates in the epitaxial layer because of a lattice constant mismatch between materials.…”

Section: Introductionmentioning

confidence: 99%

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Study on modulating the indium composition in InGaN quantum wells to improve the luminous efficiency of GaN LED

Lin

Tseng

et al. 2021

J Mater Sci: Mater Electron

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This study primarily used metal-organic chemical vapor deposition to grow gallium nitride (GaN) light-emitting diode (LED) structures with InGaN quantum wells (QWs). During the InGaN QW growing process, an identical concentration of trimethylindium gas was prepared and introduced at different times (Before(B), Middle(M), and After(A)) into the QW structures for an investigation of the variation in GaN LED luminous efficacy. Because of segregation resulting from the different concentrations of In content of the InGaN QWs during the process and because of the stress resulting from lattice mismatch between atoms, the interaction between segregation and stress forms quantum dots (QDs). Under processes with the appropriate parameters, the QDs can improve the luminous efficacy of GaN LEDs. Postprocess LEDs were measured for their electroluminescence, photoluminescence, cathodoluminescence, thermal stability, light output power, and external quantum efficiency. The QW structures were analyzed and observed using high-resolution transmission electron microscopy. The results revealed that the Before (B) LED had the greatest light output power at 46.6 mW, an increase of approximately 15.6%. Thermal annealing was then used to treat the LED at 850 °C, after which the photoluminescence intensity increased by 1.7 times.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on modulating the indium composition in InGaN quantum wells to improve the luminous efficiency of GaN LED

Lin

Tseng

et al. 2021

J Mater Sci: Mater Electron

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Failure Mechanism of Phosphors in GaN‐Based White LEDs

Cao

Sun

et al. 2019

Physica Status Solidi (a)

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The degradation and failure mechanisms of nitride phosphor in GaN-based white LEDs are studied using an in situ multi-functional accelerated life test and different analytical technologies. The electroluminescence results show that both the intensities of the blue emission (BL) from the LED chips and the yellow emission (YL) from the phosphors decrease with the stress time increasing. However, the YL/BL intensity ratio increases with a yellow shift for the chromaticity coordinates. The reason is not only due to the degradation of the LED chip but the nitride phosphors. The generated microcracks and delamination of phosphor layer lead to the increase of blue light absorption. Except for that, we find that the reason for the decrease of the phosphor conversion efficiency is related to the oxidization of the phosphor's luminescence center Eu 2þ ions instead of phosphor thermal quenching. These findings help further understand failure mechanism of phosphors during the operation, and improve the long-term color quality for the white LEDs.

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Efficiency enhancement of blue light emitting diodes by eliminating V-defects from InGaN/GaN multiple quantum well structures through GaN capping layer control

Tsai

Fang³

et al. 2018

Applied Surface Science

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Improving the Brightness and Reliability of InGaN/GaN Near Ultraviolet Light-Emitting Diodes by Controlling the Morphology of the GaN Buffer Layer

Cited by 5 publications

References 25 publications

Study on modulating the indium composition in InGaN quantum wells to improve the luminous efficiency of GaN LED

Study on modulating the indium composition in InGaN quantum wells to improve the luminous efficiency of GaN LED

Failure Mechanism of Phosphors in GaN‐Based White LEDs

Efficiency enhancement of blue light emitting diodes by eliminating V-defects from InGaN/GaN multiple quantum well structures through GaN capping layer control

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