Recent progress in red light-emitting diodes by III-nitride materials

Iida, Daisuke; Ohkawa, Kazuhiro

doi:10.1088/1361-6641/ac3962

Cited by 58 publications

(40 citation statements)

References 236 publications

(439 reference statements)

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“…These presume that the crystalline quality of the InGaN active region can be improved because the growth temperature increases due to In pulling effect. 19 InGaN-based red LEDs can grow on pseudosubstrates (e.g., InGaNOS substrate and InGaN on porous GaN). 20,21 Such LED devices have a large redshifted peak emission wavelength compared with those grown on standard GaN templates.…”

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confidence: 99%

Demonstration of 621-nm-wavelength InGaN-based single-quantum-well LEDs with an external quantum efficiency of 4.3% at 10.1 A/cm2

et al. 2022

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Here, we report highly efficient InGaN-based red light-emitting diodes (LEDs) grown on conventional c-plane-patterned sapphire substrates. An InGaN single quantum well active layer provides the red spectral emission. The 621-nm-wavelength LEDs exhibited high-purity emission with a narrow full-width at half-maximum of 51 nm. The packaged LED’s external quantum efficiency, light-output power, and forward voltage with a 621 nm peak emission wavelength at 20 mA (10.1 A/cm2) injection current were 4.3%, 1.7 mW, and 2.96 V, respectively. This design development represents a valuable contribution to the next generation of micro-LED displays.

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confidence: 99%

Demonstration of 621-nm-wavelength InGaN-based single-quantum-well LEDs with an external quantum efficiency of 4.3% at 10.1 A/cm2

et al. 2022

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“…Many efforts have been made to bridge the "green gap" [6][7][8][9]. However, up to date, the external quantum efficiency (EQE) of red InGaN LEDs is still lower than 3% [10]. Recently, N-polar LED (N-LED) has been reported to be an effective candidate to break through the bottleneck faced by Ga-LED [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

“…However, up to date, the external quantum efficiency (EQE) of red InGaN LEDs is still lower than 3% [10]. Recently, N-polar LED (N-LED) has been reported to be an effective candidate to break through the bottleneck faced by Ga-LED [10][11][12][13]. The polarization field in N-LED is in a reverse direction compared to that of Ga-LED, thus having some intrinsic merits to suppress the efficiency droop effect and carrier leakage problem [14].…”

Section: Introductionmentioning

confidence: 99%

“…In the recent years, N-polar GaN with an atomic smooth surface and reduced defects grown by metal organic chemical vapor deposition (MOCVD) has been reported by researchers [17][18][19][20], and the N-polar high electron mobility transistors (HEMTs), ultraviolet LEDs with superior performance have also been designed [21][22][23][24][25]. However, seldom experimental reports could be found for the investigation of N-polar red LEDs [10]. Moreover, as the growth conditions and the quality of epilayers are rather different for N-LED and Ga-LED (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Superior Optoelectronic Performance of N-Polar GaN LED to Ga-Polar Counterpart in the “Green Gap” Range

Jiang

Jia

et al. 2022

IEEE Access

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The low luminous efficiency of indium gallium nitride (InGaN) light-emitting diodes (LED) in the "green gap" range has been a long unsettled issue confounding the researchers. One of the main obstacles comes from the intrinsic polarization field in the incumbent Ga-polar LEDs (Ga-LEDs), where the polarization field will bend the energy band thus reducing the radiative recombination efficiency. The scenario will become different when we reverse the polarization field with the adoption of N-polar GaN, which should be a promising candidate to obtain LEDs with high luminous efficiency in the "green gap" range. In this study, the optical and electronic performances of InGaN LEDs in the "green gap" range with N-and Ga-polar have been numerically investigated. The results demonstrate that the light-output power of N-polar LED (N-LED) is ~1.69-fold higher than that of Ga-LED at a current density of 1250 A/cm 2 , thus leading to a significantly improved internal quantum efficiency. Meanwhile, the turn-on voltage of N-LED is lowered by ~17.3% compared to that of Ga-LED. As revealed by the energy band diagram, the superior optoelectronic performance of N-LED is mainly attributed to the stronger carrier confinement in the active region and the lower carrier injection barriers. This study suggests the prospective realization of high luminous efficiency InGaN LEDs in the "green gap" range by the implementation of N-LEDs.INDEX TERMS Green gap, Light-emitting diodes, light-out power, N-polar, turn-on voltage

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“…Despite such achievements, there remains many challenges to be conquered for self-assembled InGaN QDs, such as wavelength control and quantum efficiency to meet the requirements of actual device application. In addition, research on all-visible and long-wavelength LEDs has mainly focused on quantum wells [ 21 , 22 , 23 ]. Therefore, it is necessary to explore the growth conditions for the formation of InGaN QDs in detail and to optimize the growth method on this basis to obtain long-wavelength InGaN QDs.…”

Section: Introductionmentioning

confidence: 99%

Explorations on Growth of Blue-Green-Yellow-Red InGaN Quantum Dots by Plasma-Assisted Molecular Beam Epitaxy

Zhang

Yang

et al. 2022

Nanomaterials

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Self-assembled growth of blue-green-yellow-red InGaN quantum dots (QDs) on GaN templates using plasma-assisted molecular beam epitaxy were investigated. We concluded that growth conditions, including small N2 flow and high growth temperature are beneficial to the formation of InGaN QDs and improve the crystal quality. The lower In/Ga flux ratio and lower growth temperature are favorable for the formation of QDs of long emission wavelength. Moreover, the nitrogen modulation epitaxy method can extend the wavelength of QDs from green to red. As a result, visible light emissions from 460 nm to 622 nm have been achieved. Furthermore, a 505 nm green light-emitting diode (LED) based on InGaN/GaN MQDs was prepared. The LED has a low external quantum efficiency of 0.14% and shows an efficiency droop with increasing injection current. However, electroluminescence spectra exhibited a strong wavelength stability, with a negligible shift of less than 1.0 nm as injection current density increased from 8 A/cm2 to 160 A/cm2, owing to the screening of polarization-related electric field in QDs.

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Recent progress in red light-emitting diodes by III-nitride materials

Cited by 58 publications

References 236 publications

Demonstration of 621-nm-wavelength InGaN-based single-quantum-well LEDs with an external quantum efficiency of 4.3% at 10.1 A/cm2

Demonstration of 621-nm-wavelength InGaN-based single-quantum-well LEDs with an external quantum efficiency of 4.3% at 10.1 A/cm2

Superior Optoelectronic Performance of N-Polar GaN LED to Ga-Polar Counterpart in the “Green Gap” Range

Explorations on Growth of Blue-Green-Yellow-Red InGaN Quantum Dots by Plasma-Assisted Molecular Beam Epitaxy

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