Efficiency Enhancement of InGaN LEDs With an n-Type AlGaN/GaN/InGaN Current Spreading Layer

Liu, Hsueh-Hsing; Chen, Peng-Ren; Lee, Geng-Yen; Chyi, Jen-Inn

doi:10.1109/led.2011.2163490

Cited by 17 publications

(16 citation statements)

References 14 publications

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“…The NPNPN-GaN junctions can also reduce the current crowding and thus promote the lateral current spreading. As the energy barriers for the electrons in the conduction band of the n-GaN region have been generated, the NPNPN-GaN junctions increase the layer resistivity vertically, which is beneficial for better current spreading [15][16][17]. Figures 6(a) and 6(b) depict the simplified equivalent circuits of the reference device and the NPNPN-GaN device.…”

Section: Resultsmentioning

confidence: 99%

“…It has been reported that improving the p-type specific contact resistance helps to achieve a better current spreading [13,14]. Meanwhile, it has been also shown that the current crowding decreases when the device is more resistive vertically [12], and an n-type InGaN current spreading layer has therefore been proposed to realize a better current spreading [15,16]. Due to the relatively low growth temperature the crystal quality of the n-type InGaN current spreading layer would be inferior to that of hightemperature grown GaN, which may give rise to non-radiative recombination defects.…”

Section: Introductionmentioning

confidence: 99%

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On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

Kyaw¹,

Zhang²,

Liu³

et al. 2014

Opt. Express

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N-GaN/P-GaN/N-GaN/P-GaN/N-GaN (NPNPN-GaN) junctions embedded between the n-GaN region and multiple quantum wells (MQWs) are systematically studied both experimentally and theoretically to increase the performance of InGaN/GaN light emitting diodes (LEDs) in this work. In the proposed architecture, each thin P-GaN layer sandwiched in the NPNPN-GaN structure is completely depleted due to the built-in electric field in the NPNPN-GaN junctions, and the ionized acceptors in these P-GaN layers serve as the energy barriers for electrons from the n-GaN region, resulting in a reduced electron over flow and enhanced the current spreading horizontally in the n-GaN region. These lead to increased optical output power and external quantum efficiency (EQE) from the proposed device.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

Kyaw¹,

Zhang²,

Liu³

et al. 2014

Opt. Express

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“…In this paper, we replace the conventional n-AlGaN layer with a 60-period stacked Si modulation-doped 20-nm n-AlGaN/15-nm u-GaN structure to obtain a well-distributed current. A multi-layer stacked n-AlGaN/u-GaN structure not only reduces the dislocation density, but also improves the electron concentration, weakens electron scattering, and increases electron mobility [25,26]. Here, it is worth noting that devices with a multi-layer stacking structure exhibit a 22% and 26.5% enhancement in the output power and external quantum efficiency (EQE), respectively, under a 20-mA injection current.…”

Section: Introductionmentioning

confidence: 99%

Using a Multi-Layer Stacked AlGaN/GaN Structure to Improve the Current Spreading Performance of Ultraviolet Light-Emitting Diodes

Wang

Zhang

et al. 2020

Materials

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To obtain excellent current spreading performance of ultraviolet light-emitting diodes (UVLEDs), a 60-period stacked Si modulation-doped n-AlGaN/u-GaN structure is proposed to replace the traditional n-AlGaN structure. The high-resolution X-ray diffraction ω-scan rocking curves show that the periodic growth of AlGaN and GaN layers plays a positive role in reducing dislocation density. Compared with the conventional UV light-emitting diodes (LEDs), light emission micrographs of devices with a multi-layer stacked n-AlGaN/u-GaN structure reveal higher brightness and a more uniform distribution. In addition, the output power and external quantum efficiency under a 20-mA injection current are increased by 22% and 26.5%, respectively. Experimental and simulation results indicate that a multi-layer stacking structure can alleviate the current crowding effect in four ways:(1) a reduction in dislocation density; (2) replacement of quasi-two-dimensional electron transport with electronic bulk transport to enhance electron mobility; (3) an increase in electron concentration without improving the impurity concentration; and (4) a weakening of the electron scattering effect by reducing the impurity concentration.

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“…LEDs are the most important lighting devices in the future due to their advantages in terms of environmental protection, long lifetime, and vivid color. However, some existing mechanisms of the LEDs can still lead to the efficiency droop effect, such as electron overflow loss [1][2][3], lacking in hole injection [4,5], Auger recombination [6][7][8], carrier delocalization [9,10], junction heating [11], and current crowding [12].…”

Section: Introductionmentioning

confidence: 99%

Investigating the Efficiency Droop of Nitride-Based Blue LEDs with Different Quantum Barrier Growth Rates

Wang¹,

Chiou²,

Chang³

2019

Crystals

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In this study, GaN-based blue InGaN/GaN light-emitting diodes (LEDs) with different growth rates of the quantum barriers were fabricated and investigated. The LEDs with quantum barriers grown with a higher growth rate exhibit a lower leakage current and less non-radiative recombination centers in the multiple quantum wells (MQWs). Therefore, the LED with a higher barrier growth rate achieves a better light output power by 18.4% at 120 mA, which is attributed to weaker indium fluctuation effect in the QWs. On the other hand, the localized states created by indium fluctuation lead to a higher local carrier density, and Auger recombination in the QWs. Thus, the efficiency droop ratio of the LEDs with a higher barrier growth rate was only 28.6%, which was superior to that with a lower barrier growth rate (39.3%).

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Efficiency Enhancement of InGaN LEDs With an n-Type AlGaN/GaN/InGaN Current Spreading Layer

Cited by 17 publications

References 14 publications

On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes

Using a Multi-Layer Stacked AlGaN/GaN Structure to Improve the Current Spreading Performance of Ultraviolet Light-Emitting Diodes

Investigating the Efficiency Droop of Nitride-Based Blue LEDs with Different Quantum Barrier Growth Rates

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