Characteristics of efficiency droop in GaN-based light emitting diodes with an insertion layer between the multiple quantum wells and n-GaN layer

Chang, Shih-sen; Chiu, C. H.; Li, J. C.; Lu, Yu-Hsuan; Li, Z. Y.; Yang, Hung‐Chih; Kuo, Hao‐Chung; Lu, Tien‐Chang; Wang, S. C.

doi:10.1063/1.3531957

Cited by 34 publications

(15 citation statements)

References 21 publications

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“…Additionally, highly strained InGaN/GaN green multiple quantum wells (MQWs), due to a large lattice mismatch between the high-In-content InGaN and the GaN, exhibit strong piezoelectric-field-induced quantum-confined stark effects (QCSE), resulting in a spatial separation of the wave functions of electrons and holes in the quantum well [ 15 , 16 ]. In the past few decades, much scientific effort has focused on approaches to improve the optical and electrical properties of green LEDs [ 17 , 18 , 19 ]. It was found that hexagonal V-pits having inverted pyramids with (10-11) faceted sidewalls were generally formed in InGaN/GaN MQWs [ 20 , 21 , 22 , 23 ].…”

Section: Introductionmentioning

confidence: 99%

An InGaN/GaN Superlattice to Enhance the Performance of Green LEDs: Exploring the Role of V-Pits

et al. 2018

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Despite the fact that an InGaN/GaN superlattice (SL) is useful for enhancing the performance of a GaN-based light-emitting diode (LED), its role in improving the efficiency of green LEDs remains an open question. Here, we investigate the influence of a V-pits-embedded InGaN/GaN SL on optical and electrical properties of GaN-based green LEDs. We recorded a sequence of light emission properties of InGaN/GaN multiple quantum wells (MQWs) grown on a 0- and 24-pair InGaN/GaN SL by using scanning electron microscopy (SEM) in combination with a room temperature cathodoluminescence (CL) measurement, which demonstrated the presence of a potential barrier formed by the V-pits around threading dislocations (TDs). We find that an increase in V-pit diameter would lead to the increase of V-pit potential barrier height. Our experimental data suggest that a V-pits-embedded, 24-pair InGaN/GaN SL can effectively suppress the lateral diffusion of carriers into non-recombination centers. As a result, the external quantum efficiency (EQE) of green LEDs is improved by 29.6% at an injection current of 20 mA after implementing the V-pits-embedded InGaN/GaN SL layer. In addition, a lower reverse leakage current was achieved with larger V-pits.

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Section: Introductionmentioning

confidence: 99%

An InGaN/GaN Superlattice to Enhance the Performance of Green LEDs: Exploring the Role of V-Pits

et al. 2018

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“…Most of these approaches involve inserting a buffer layer between the sapphire wafer and LED active structure, like a low-temperature GaN layer [1], AlN or AlGaN layer [2], SiO 2 layer with openings for overgrowth [3], or a short period superlattice (SL) [4]. It has been demonstrated that the SL insertion layer results in increase of IQE [5,6] and smaller photoluminescence (PL) peak shift with injection [4] due to supposedly smaller defect density and lower internal electrical fields. SL was also used to improve the electroluminescence due to better hole injection and current spreading [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of quantum efficiency in InGaN quantum wells by using superlattice interlayers and pulsed growth

Nomeika¹,

Dmukauskas²,

Aleksiejūnas³

et al. 2016

Lith. J. Phys.

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Enhancement of internal quantum efficiency (IQE) in InGaN quantum wells by insertion of a superlattice interlayer and applying the pulsed growth regime is investigated by a set of time-resolved optical techniques. A threefold IQE increase was achieved in the structure with the superlattice. It was ascribed to the net effect of decreased internal electrical field due to lower strain and altered carrier localization conditions. Pulsed MOCVD growth also resulted in twice higher IQE, presumably due to better control of defects in the structure. An LED (light emitting diode) structure with a top p-type contact GaN layer was manufactured by using both growth techniques with the peak IQE equal to that in the underlying quantum well structure. The linear recombination coefficient was found to gradually increase with excitation due to carrier delocalization, and the latter dependence was successfully used to fit the IQE droop.

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“…The main mechanisms of the efficiency droop effect have been described, including carrier delocalization, 3,4 carrier leakage, 5,6 defects, 7 junction heating, 8 and Auger recombination. [12][13][14] Recently, some researchers have designed some structures of staggered QWs, [15][16][17] InGaN-delta-AlGaN or InN QWs, 18,19 strain-compensated QWs, 20,21 and graded-composition barriers, 22 to improve the optical properties of nitridebased LEDs. 11 These effects limit the use of LEDs in various applications where high-current and high-temperature operations are required.…”

Section: Introductionmentioning

confidence: 99%

Investigation of optical and electrical properties of GaN-based blue light-emitting diodes with various quantum well thicknesses

et al. 2015

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Optical and electrical properties of gallium nitride (GaN)-based blue light-emitting diodes (LEDs) with various indium gallium nitride (InGaN) quantum well (QW) thicknesses were investigated. As the QW thickness was increased, the light output power of GaNbased LEDs also increased. The increase can be attributed to the increase in the carrier radiative recombination rate in the active region. However, the turn-on voltages of these fabricated LEDs are different. This was attributed to the increase in the polarization field with increasing QW thickness. In regard to the hot/cold factor, LEDs with a thicker QW achieved better performance at a low-injection current owing to the lower defect density. The hot/cold factor at a high-injection current would be mainly influenced by the efficiency droop mechanism.

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Characteristics of efficiency droop in GaN-based light emitting diodes with an insertion layer between the multiple quantum wells and n-GaN layer

Cited by 34 publications

References 21 publications

An InGaN/GaN Superlattice to Enhance the Performance of Green LEDs: Exploring the Role of V-Pits

An InGaN/GaN Superlattice to Enhance the Performance of Green LEDs: Exploring the Role of V-Pits

Enhancement of quantum efficiency in InGaN quantum wells by using superlattice interlayers and pulsed growth

Investigation of optical and electrical properties of GaN-based blue light-emitting diodes with various quantum well thicknesses

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