Internal quantum efficiency improvement of InGaN/GaN multiple quantum well green light-emitting diodes

Zhou, Quanbin; Xu, Miao; Wang, H.

doi:10.1515/oere-2016-0004

Cited by 26 publications

(24 citation statements)

References 42 publications

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“…Energies 2017, 10, 1277 3 of 8 and 7.5 × 10 17 cm −3 and 8 cm 2 /(V•s) in p-type GaN grown at 950 °C, respectively [22,23]. Light outputcurrent-voltage (L-I-V) characteristics for top-emitting packaged blue and green LEDs were measured at temperatures ranging from 80 to 300 K by using a vacuum chamber probe station equipped with an Agilent B2902 precision source-measurement unit.…”

Section: Resultsmentioning

confidence: 99%

“…For such a difference in wavelength (450 nm versus 520 nm), the In mole fraction in the quantum wells of the green LEDs was~22%, i.e., higher than in those of the blue LEDs,~14%, which was enabled by reducing the growth temperature for the active region and subsequent p-type layers (1050 • C and 950 • C for the blue and green LEDs, respectively). The typical values of hole concentration and mobility were about 1.1 × 10 18 cm −3 and 16 cm 2 /(V·s) in p-type GaN grown at 1050 • C, and 7.5 × 10 17 cm −3 and 8 cm 2 /(V·s) in p-type GaN grown at 950 • C, respectively [22,23]. Light output-current-voltage (L-I-V) characteristics for top-emitting packaged blue and green LEDs were measured at temperatures ranging from 80 to 300 K by using a vacuum chamber probe station equipped with an Agilent B2902 precision source-measurement unit.…”

Section: Methodsmentioning

confidence: 98%

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The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

et al. 2017

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Abstract:The effect of strongly-imbalanced carrier concentration and mobility on efficiency droop is studied by comparing the onset voltage of high injection, the onset current density of the droop, and the magnitude of the droop, as well as their temperature dependence, of GaInN-based blue and green light-emitting diodes (LEDs). An n-to-p asymmetry factor is defined as σ n /σ p , and was found to be 17.1 for blue LEDs and 50.1 for green LEDs. Green LEDs, when compared to blue LEDs, were shown to enter the high-injection regime at a lower voltage, which is attributed to their less favorable p-type transport characteristics. Green LEDs, with lower hole concentration and mobility, have a lower onset current density of the efficiency droop and a higher magnitude of the efficiency droop when compared to blue LEDs. The experimental results are in quantitative agreement with the imbalanced carrier transport causing the efficiency droop, thus providing guidance for alleviating the phenomenon of efficiency droop.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 98%

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

et al. 2017

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“…In previous reports, determining the interface between the HI-InGaN well and the GaN barrier was difficult for HI-InGaN/GaN QWs grown by the conventional growth mode. In addition, many In-rich clusters were generated in the HI-InGaN well 19 . However, in this work, the interface between the In 0.45 Ga 0.55 N well and the In 0.13 Ga 0.87 N barrier for the In 0.45 Ga 0.55 N/In 0.13 Ga 0.87 N QWs is relatively more distinct and higher quality than those of the previous results 20 , 21 .…”

Section: Resultsmentioning

confidence: 99%

Flower-Like Internal Emission Distribution of LEDs with Monolithic Integration of InGaN-based Quantum Wells Emitting Narrow Blue, Green, and Red Spectra

Lee

Choi

Lee

et al. 2017

Sci Rep

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We report a phosphor-free white light-emitting diodes (LED) realized by the monolithic integration of In0.18Ga0.82N/GaN (438 nm, blue), In0.26Ga0.74N/GaN (513 nm, green), and In0.45Ga0.55N/In0.13Ga0.87N (602 nm, red) quantum wells (QWs) as an active medium. The QWs corresponding to blue and green light were grown using a conventional growth mode. For the red spectral emission, five-stacked In0.45Ga0.55N/In0.13Ga0.87N QWs were realized by the so-called Ga-flow-interruption (Ga-FI) technique, wherein the Ga supply was periodically interrupted during the deposition of In0.3Ga0.7N to form an In0.45Ga0.55N well. The vertical and lateral distributions of the three different light emissions were investigated by fluorescence microscope (FM) images. The FM image measured at a focal point in the middle of the n-GaN cladding layer for the red-emitting LED shows that light emissions with flower-like patterns with six petals are periodically observed. The chromaticity coordinates of the electroluminescence spectrum for the white LEDs at an injection current of 80 mA are measured to be (0.316, 0.312), which is close to ideal white light. In contrast with phosphor-free white-light-emitting devices based on nanostructures, our white light device exhibits a mixture of three independent wavelengths by monolithically grown InGaN-based QWs, thus demonstrating a more facile technique to obtain white LEDs.

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“…The efficiency of blue LEDs is very high, and blue LEDs have been commercially used in many fields, such as lighting [ 3 , 4 , 5 , 6 ], display [ 7 , 8 ], light communication [ 9 , 10 ], back lighting [ 11 , 12 ], and so on. However, the internal quantum efficiency (IQE) of GaN-based green LEDs is still lower than that of blue LEDs, which is called the “Green Gap” [ 13 ]. It obstructs the green LED to be applied in Red-Green-Blue (RGB) lighting, full-color displays, and visible-light communication.…”

Section: Introductionmentioning

confidence: 99%

Quantum Efficiency Enhancement of a GaN-Based Green Light-Emitting Diode by a Graded Indium Composition p-Type InGaN Layer

Zhou

Wang

et al. 2018

Nanomaterials

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We propose a graded indium composition p-type InGaN (p-InGaN) conduction layer to replace the p-type AlGaN electron blocking layer and a p-GaN layer in order to enhance the light output power of a GaN-based green light-emitting diode (LED). The indium composition of the p-InGaN layer decreased from 10.4% to 0% along the growth direction. The light intensity of the LED with a graded indium composition p-InGaN layer is 13.7% higher than that of conventional LEDs according to the experimental result. The calculated data further confirmed that the graded indium composition p-InGaN layer can effectively improve the light power of green LEDs. According to the simulation, the increase in light output power of green LEDs with a graded indium composition p-InGaN layer was mainly attributed to the enhancement of hole injection and the improvement of the radiative recombination rate.

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Internal quantum efficiency improvement of InGaN/GaN multiple quantum well green light-emitting diodes

Abstract: In recent years, GaN−based light−emitting diode (LED) has been widely used in various applications

Cited by 26 publications

References 42 publications

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

The Effect of Imbalanced Carrier Transport on the Efficiency Droop in GaInN-Based Blue and Green Light-Emitting Diodes

Flower-Like Internal Emission Distribution of LEDs with Monolithic Integration of InGaN-based Quantum Wells Emitting Narrow Blue, Green, and Red Spectra

Quantum Efficiency Enhancement of a GaN-Based Green Light-Emitting Diode by a Graded Indium Composition p-Type InGaN Layer

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