Effects of a Reduced Effective Active Region Volume on Wavelength-Dependent Efficiency Droop of InGaN-Based Light-Emitting Diodes

Li, Panpan; Zhao, Y. B.; Yi, Xiaoyan; Li, Hongjian

doi:10.3390/app8112138

Cited by 6 publications

(5 citation statements)

References 33 publications

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“…A modified ABC model with the consideration of the shrink of InGaN QW is employed in our previous study to investigate the carrier recombination dynamics in InGaN MQWs. IQE can be calculated by [24,25], where I is the current injected into the active region, V active is the physical volume of the active region, and q is the elementary charge. Due to the localized carriers in the potential minima of In-rich InGaN clusters [26][27][28], it is reported that the effective active region volume (V effective ) is smaller than the V active .…”

Section: Resultsmentioning

confidence: 99%

“…The external quantum efficiency (EQE) is calculated by, where P output and hν are the output power and photonic energy. In our experiment, the light extraction efficiency (LEE) is assumed to be 0.8 for the high-efficiency InGaN LEDs grown on PSS and it has been used in our previous study [24]. Therefore, the IQE can be achieved by considering the LEE as IQE = EQE/LEE.…”

Section: Resultsmentioning

confidence: 99%

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Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well

Zhao

2019

Applied Sciences

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We demonstrate an ultra-low efficiency droop in c-plane polar InGaN blue light-emitting diodes (LEDs) by reducing the carrier density using a wide InGaN last quantum well (LQW). It is found that the LEDs with a 5.2 nm thick LQW show a negligible efficiency droop, with an external quantum efficiency (EQE) reducing from a peak value of 38.8% to 36.4% at 100 A/cm2 and the onset-droop current density is raised from 3 A/cm2 to 40 A/cm2 as the LQW thickness increases from 3.0 nm to 5.2 nm. The analysis based on the ABC model indicates that small efficiency droop is caused by the reduced carrier density using a wide LQW. The peak efficiency is reduced with a wide LQW, which is caused by the reduction of the electron-hole wavefunction overlap and the deterioration of the crystal quality of the InGaN layer. This study suggests that the application of the InGaN LEDs with a wide LQW can be a promising and simple remedy for achieving high efficiency at a high current density.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well

Zhao

2019

Applied Sciences

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“…The assumed value is lower than the values for semipolar devices reported in [32,40]. However, for the modeled structures, Auger recombination has the least influence on laser performance of all recombination processes [41]. For quantum wells with a wide bandgap this process may even be neglected entirely.…”

Section: Diffusion and Recombination Coefficientsmentioning

confidence: 89%

Bulletin of the Polish Academy of Sciences: Technical Sciences

Kuc

Sokół

Piskorski

et al. 2020

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This paper presents the results of a numerical analysis of nitride-based edge-emitting lasers with an InGaN/GaN active region designed for continuous wave room temperature emission of green and blue light. The main goal was to investigate whether the indium thin oxide (ITO) layer can serve as an effective optical confinement improving operation of these devices. Simulations were performed with the aid of a self-consistent thermal-electrical-optical model. Results obtained for green-and blue-emitting lasers were compared. The ITO layer in the p-type cladding was found to effectively help confine the laser mode in the active regions of the devices and to decrease the threshold current density.

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“…This results in the reduction of the effective active volume, which contributes to the radiative recombination of electrons and holes. It has been reported that a reduction in the effective active volume of InGaN MQWs leads to a substantial increase in the efficiency droop [16][17][18][19][20]. Therefore, the influence of the internal electric field on the efficiency droop is expected to be explained by the reduced effective active volume due to the increasing internal field strength.…”

Section: Introductionmentioning

confidence: 99%

Efficiency Droop and Effective Active Volume in GaN-Based Light-Emitting Diodes Grown on Sapphire and Silicon Substrates

Ryu

Onwukaeme

2019

Applied Sciences

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We compared the efficiency droop of InGaN multiple-quantum-well (MQW) blue light-emitting diode (LED) structures grown on silicon(111) and c-plane sapphire substrates and analyzed the efficiency droop characteristics using the rate equation model with reduced effective active volume. The efficiency droop of the LED sample on silicon was observed to be reduced considerably compared with that of the identical LED sample on sapphire substrates. When the measured external quantum efficiency was fitted with the rate equation model, the effective active volume of the MQW on silicon was found to be ~1.45 times larger than that of the MQW on sapphire. The lower efficiency droop in the LED on silicon could be attributed to its larger effective active volume compared with the LED on sapphire. The simulation results showed that the effective active volume decreased as the internal electric fields increased, as a result of the reduced overlap of the electron and hole distribution inside the quantum well and the inhomogeneous carrier distribution in the MQWs. The difference in the internal electric field of the MQW between the LED on silicon and sapphire could be a major reason for the difference in the effective active volume, and consequently, the efficiency droop.

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Effects of a Reduced Effective Active Region Volume on Wavelength-Dependent Efficiency Droop of InGaN-Based Light-Emitting Diodes

Cited by 6 publications

References 33 publications

Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well

Toward Ultra-Low Efficiency Droop in C-Plane Polar InGaN Light-Emitting Diodes by Reducing Carrier Density with a Wide InGaN Last Quantum Well

Bulletin of the Polish Academy of Sciences: Technical Sciences

Efficiency Droop and Effective Active Volume in GaN-Based Light-Emitting Diodes Grown on Sapphire and Silicon Substrates

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