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Open AccessArticle

A Simulation Study of Carrier Capture Ability of the Last InGaN Quantum Well with Different Indium Content for Yellow-Light-Emitting InGaN/GaN Multiple Quantum Wells

by Wei Liu, Zeyu Liu, Hengyan Zhao and Junjie Gao

Micromachines 2023, 14(9), 1669; https://doi.org/10.3390/mi14091669 - 26 Aug 2023

Cited by 3 | Viewed by 1968

Abstract

Currently, GaN-based blue- and green-light-emitting devices have achieved successful applications in practice, while the luminescence efficiency of devices with longer wavelengths (such as yellow light) is still very low. Therefore, in this paper, the electroluminescence characterization of yellow-light-emitting InGaN/GaN multiple quantum wells (MQWs) [...] Read more.

Currently, GaN-based blue- and green-light-emitting devices have achieved successful applications in practice, while the luminescence efficiency of devices with longer wavelengths (such as yellow light) is still very low. Therefore, in this paper, the electroluminescence characterization of yellow-light-emitting InGaN/GaN multiple quantum wells (MQWs) with different In content in the last InGaN quantum well, which is next to the p-type GaN electrode layer, are investigated numerically to reveal a possible physical mechanism by which the different distribution of In content in the active region impacts the carrier capture and the light emission process in yellow InGaN/GaN MQWs. The simulation results show that at low injection currents, the luminescence efficiency of high-In-content yellow MQWs is enhanced, which can be ascribed to the enhanced radiative recombination process induced by the increased carrier concentration in the last InGaN quantum wells with promoted carrier capture ability. However, in the case of high injection condition, the luminescence efficiency of yellow MQWs deteriorates with increasing In content, i.e., the droop effect becomes remarkable. This can be ascribed to both significantly enhanced Auger recombination and electron leakage in the last InGaN quantum well, induced also by the promoted capture ability of charge carriers. Full article

(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications)

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11 pages, 4657 KB

Open AccessArticle

Influence of Low-Temperature Cap Layer Thickness on Luminescence Characteristics of Green InGaN/GaN Quantum Wells

by Haoran Sun, Yuhui Chen, Yuhao Ben, Hongping Zhang, Yujie Zhao, Zhihao Jin, Guoqi Li and Mei Zhou

Materials 2023, 16(4), 1558; https://doi.org/10.3390/ma16041558 - 13 Feb 2023

Viewed by 2279

Abstract

GaN cap layer with different thicknesses was grown on each InGaN well layer during MOCVD growth for InGaN/GaN multiple quantum well (MQW) samples to study the influence of the cap layer on the photoluminescence (PL) characteristics of MQWs. Through the temperature-dependent (TD) PL [...] Read more.

GaN cap layer with different thicknesses was grown on each InGaN well layer during MOCVD growth for InGaN/GaN multiple quantum well (MQW) samples to study the influence of the cap layer on the photoluminescence (PL) characteristics of MQWs. Through the temperature-dependent (TD) PL spectra, it was found that when the cap layer was too thick, the localized states of the quantum wells were relatively non-uniform. The thicker the well layer, the worse the uniformity of the localized states. Furthermore, through micro-area fluorescence imaging tests, it was found that when the cap layer was too thick, the luminescence quality of the quantum well was worse. In summary, the uniformity of the localized states in the quantum wells and the luminescence characteristics of the quantum wells could be improved when a relatively thin cap layer of the quantum well was prepared during the growth. These results could facilitate high efficiency QW preparation, especially for green LEDs. Full article

(This article belongs to the Section Optical and Photonic Materials)

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11 pages, 2237 KB

Open AccessArticle

Investigation into the MOCVD Growth and Optical Properties of InGaN/GaN Quantum Wells by Modulating NH₃ Flux

by Zhenyu Chen, Feng Liang, Degang Zhao, Jing Yang, Ping Chen and Desheng Jiang

Crystals 2023, 13(1), 127; https://doi.org/10.3390/cryst13010127 - 10 Jan 2023

Cited by 6 | Viewed by 3453

Abstract

In this study, the surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied by applying different flow rates of ammonia during MOCVD growth, and the best growth conditions of InGaN layers for green laser diodes were explored. Different emission peak [...] Read more.

In this study, the surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied by applying different flow rates of ammonia during MOCVD growth, and the best growth conditions of InGaN layers for green laser diodes were explored. Different emission peak characteristics were observed in temperature-dependent photoluminescence (TDPL) examination, which showed significant structural changes in InGaN layers and in the appearance of composite structures of InGaN/GaN quantum wells and quantum-dot-like centers. It was shown that these changes are caused by several effects induced by ammonia, including both the promotion of indium corporation and corrosion from hydrogen caused by the decomposition of ammonia, as well as the decrease in the surface energy of InGaN dot-like centers. We carried out detailed research to determine ammonia’s mechanism of action during InGaN layer growth. Full article

(This article belongs to the Special Issue III-Nitride Materials: Properties, Growth, and Applications)

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10 pages, 4452 KB

Open AccessArticle

Epitaxial Lateral Overgrowth of {11-22} InGaN Layers Using Patterned InGaN Template and Improvement of Optical Properties from Multiple Quantum Wells

by Narihito Okada and Kazuyuki Tadatomo

Crystals 2022, 12(10), 1373; https://doi.org/10.3390/cryst12101373 - 27 Sep 2022

Cited by 1 | Viewed by 1995

Abstract

We report the growth and characterization of thick, completely relaxed {11-22}-oriented InGaN layers using epitaxial lateral overgrowth (ELO). Although it was difficult to grow ELO-InGaN layers on patterned GaN templates, we succeeded in growing ELO-InGaN layers on a patterned InGaN template. The full [...] Read more.

We report the growth and characterization of thick, completely relaxed {11-22}-oriented InGaN layers using epitaxial lateral overgrowth (ELO). Although it was difficult to grow ELO-InGaN layers on patterned GaN templates, we succeeded in growing ELO-InGaN layers on a patterned InGaN template. The full width at half maximum of the X-ray rocking curve of ELO-InGaN on the InGaN templates was less than that of non-ELO InGaN. The photoluminescence intensity of InGaN/GaN multiple quantum wells on ELO-InGaN was approximately five times stronger than that on the {11-22} GaN template. Full article

(This article belongs to the Special Issue III-Nitride-Based Light-Emitting Devices)

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11 pages, 7111 KB

Open AccessArticle

Effect of Hydrogen Treatment on Photoluminescence and Morphology of InGaN Multiple Quantum Wells

by Yachen Wang, Feng Liang, Degang Zhao, Yuhao Ben, Jing Yang, Zongshun Liu and Ping Chen

Nanomaterials 2022, 12(18), 3114; https://doi.org/10.3390/nano12183114 - 8 Sep 2022

Cited by 4 | Viewed by 2356

Abstract

In this paper, the photoluminescence (PL) properties and surface morphology of InGaN/GaN multiple quantum well (MQW) structures with the hydrogen (H₂) heat treatment of InGaN are investigated to elucidate the effect of hydrogen on the structure and surface of the MQWs. [...] Read more.

In this paper, the photoluminescence (PL) properties and surface morphology of InGaN/GaN multiple quantum well (MQW) structures with the hydrogen (H₂) heat treatment of InGaN are investigated to elucidate the effect of hydrogen on the structure and surface of the MQWs. The experimental results show that the H₂ heat treatment on the as-grown MQWs may lead to the decomposition of InGaN and the formation of inhomogeneous In clusters. The atomic force microscope (AFM) study indicates that although the surface roughness of the uncapped samples increases after H₂ treatment, the V-defects are suppressed. Moreover, the luminescence efficiency of the MQWs can be effectively improved by growing a GaN cap layer with an appropriate thickness on the top of the MQWs, which can reduce the effects of the H₂ atmosphere and high temperature on the MQWs. In addition, a morphologic transformation from step bunching to shallow steps occurs and a much smoother surface can be obtained when a thicker cap layer is adopted. Full article

(This article belongs to the Special Issue III-N Based Semiconductor Nanomaterials for Photonic and Electronic Devices)

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19 pages, 4046 KB

Open AccessArticle

Resonant Tunneling of Electrons and Holes through the In_xGa_1−xN/GaN Parabolic Quantum Well/LED Structure

by Hind Althib

Crystals 2022, 12(8), 1166; https://doi.org/10.3390/cryst12081166 - 19 Aug 2022

Cited by 1 | Viewed by 2885

Abstract

Models describing the tunneling of electrons and holes through parabolic In_xGa_1−xN/GaN quantum well/LED structures with respect to strain were developed. The transmission coefficient, tunneling lifetime, and efficiency of LED structures were evaluated by solving the Schrödinger equation. The effects [...] Read more.

Models describing the tunneling of electrons and holes through parabolic In_xGa_1−xN/GaN quantum well/LED structures with respect to strain were developed. The transmission coefficient, tunneling lifetime, and efficiency of LED structures were evaluated by solving the Schrödinger equation. The effects of the mole fraction on the structure strain, resonant tunneling and tunneling lifetime, and LH–HH splitting were characterized. The value of LH–HH splitting increased and remained higher than the Fermi energy; therefore, only the HH band was dominant in terms of the valence band properties. The results indicate that an increase in the mole fraction can lead to efficiency droop. Full article

(This article belongs to the Special Issue Preparation and Characterization of Optoelectronic Functional Films)

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11 pages, 2910 KB

Open AccessArticle

Strain Relaxation Effect on the Peak Wavelength of Blue InGaN/GaN Multi-Quantum Well Micro-LEDs

by Chaoqiang Zhang, Ke Gao, Fei Wang, Zhiming Chen, Philip Shields, Sean Lee, Yanqin Wang, Dongyan Zhang, Hongwei Liu and Pingjuan Niu

Appl. Sci. 2022, 12(15), 7431; https://doi.org/10.3390/app12157431 - 24 Jul 2022

Cited by 14 | Viewed by 3759

Abstract

In this paper, the edge strain relaxation of InGaN/GaN MQW micro-pillars is studied. Micro-pillar arrays with a diameter of 3–20 μm were prepared on a blue GaN LED wafer by inductively coupled plasma (ICP) etching. The peak wavelength shift caused by edge strain [...] Read more.

In this paper, the edge strain relaxation of InGaN/GaN MQW micro-pillars is studied. Micro-pillar arrays with a diameter of 3–20 μm were prepared on a blue GaN LED wafer by inductively coupled plasma (ICP) etching. The peak wavelength shift caused by edge strain relaxation was tested using micro-LED pillar array room temperature photoluminescence (PL) spectrum measurements. The results show that there is a nearly 3 nm peak wavelength shift between the micro-pillar arrays, caused by a high range of the strain relaxation region in the small size LED pillar. Furthermore, a 19 μm micro-LED pillar’s Raman spectrum was employed to observe the pillar strain relaxation. It was found that the Raman E₂^H mode at the edge of the micro-LED pillar moved to high frequency, which verified an edge strain relaxation of = 0.1%. Then, the exact strain and peak wavelength distribution of the InGaN quantum wells were simulated by the finite element method, which provides effective verification of our PL and Raman strain relaxation analysis. The results and methods in this paper provide good references for the design and analysis of small-size micro-LED devices. Full article

(This article belongs to the Special Issue Optoelectronic Materials, Devices, and Applications)

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10 pages, 2999 KB

Open AccessArticle

Effect of High Temperature Treatment on the Photoluminescence of InGaN Multiple Quantum Wells

by Yachen Wang, Feng Liang, Degang Zhao, Yuhao Ben, Jing Yang, Zongshun Liu and Ping Chen

Crystals 2022, 12(6), 839; https://doi.org/10.3390/cryst12060839 - 14 Jun 2022

Cited by 5 | Viewed by 2665

Abstract

In this work, the photoluminescence (PL) properties of three as-grown InGaN/GaN multiple quantum well (MQW) structures which are heat-treated under different temperatures with nitrogen (N₂) atmosphere are investigated. Temperature-dependent photoluminescence (PL) analysis was used to characterize the depth of localized states [...] Read more.

In this work, the photoluminescence (PL) properties of three as-grown InGaN/GaN multiple quantum well (MQW) structures which are heat-treated under different temperatures with nitrogen (N₂) atmosphere are investigated. Temperature-dependent photoluminescence (PL) analysis was used to characterize the depth of localized states and defect density formed in MQWs. By fitting the positions of luminescence peaks with an LSE model, we find that deeper localized states are formed in the MQWs after high-temperature treatment. The experimental results show that the luminescence intensity of the sample heat-treated at 880 °C is significantly improved, which may be due to the shielding effect of In clusters on defects. While the luminescence efficiency decreases because of the higher defect density caused by the decomposition of the InGaN QW layer when the sample is heat-treated at 1020 °C. Moreover, the atomic force microscope results show that the increase in heat-treatment temperature leads to an increase in the width of surface steps due to the rearrangement of surface atoms in a high-temperature environment. Full article

(This article belongs to the Special Issue Preparation and Characterization of Optoelectronic Functional Films)

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11 pages, 4863 KB

Open AccessArticle

Demonstration of Efficient Ultrathin Side-Emitting InGaN/GaN Flip-Chip Light-Emitting Diodes by Double Side Reflectors

by Tae Kyoung Kim, Abu Bashar Mohammad Hamidul Islam, Yu-Jung Cha, Seung Hyun Oh and Joon Seop Kwak

Nanomaterials 2022, 12(8), 1342; https://doi.org/10.3390/nano12081342 - 13 Apr 2022

Cited by 1 | Viewed by 3299

Abstract

This work proposes an InGaN/GaN multiple-quantum-well flip-chip blue ultrathin side-emitting (USE) light-emitting diode (LED) and describes the sidewall light emission characteristics for the application of backlight units in display technology. The USE-LEDs are fabricated with top (ITO/distributed Bragg reflector) and bottom (Ag) mirrors [...] Read more.

This work proposes an InGaN/GaN multiple-quantum-well flip-chip blue ultrathin side-emitting (USE) light-emitting diode (LED) and describes the sidewall light emission characteristics for the application of backlight units in display technology. The USE-LEDs are fabricated with top (ITO/distributed Bragg reflector) and bottom (Ag) mirrors that cause light emission from the four sidewalls in a lateral direction. The effect of light output power (LOP) on lateral direction is consistently investigated for improving the optoelectronic performances of USE-LEDs. Initially, the reference USE-LED suffers from very low LOP because of poor light extraction efficiency (LEE). Therefore, the LEE is improved by fabricating ZnO nanorods at each sidewall through hydrothermal method. The effects of ZnO nanorod lengths and diameters on LOP are systematically investigated for optimizing the dimensions of ZnO nanorods. The optimized ZnO nanorods improve the LEE of USE-LED, which thus results in increasing the LOP > 80% compared to the reference LED. In addition, the light-tools simulator is also used for elucidating the increase in LEE of ZnO nanorods USE-LED. Full article

(This article belongs to the Special Issue III-N Based Semiconductor Nanomaterials for Photonic and Electronic Devices)

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9 pages, 1498 KB

Open AccessArticle

Reduction in the Photoluminescence Intensity Caused by Ultrathin GaN Quantum Barriers in InGaN/GaN Multiple Quantum Wells

by Wei Liu, Feng Liang, Degang Zhao, Jing Yang, Ping Chen and Zongshun Liu

Crystals 2022, 12(3), 339; https://doi.org/10.3390/cryst12030339 - 28 Feb 2022

Cited by 5 | Viewed by 3045

Abstract

The optical properties of InGaN/GaN violet light-emitting multiple quantum wells with different thicknesses of GaN quantum barriers are investigated experimentally. When the barrier thickness decreases from 20 to 10 nm, the photoluminescence intensity at room temperature increases, which can be attributed to the [...] Read more.

The optical properties of InGaN/GaN violet light-emitting multiple quantum wells with different thicknesses of GaN quantum barriers are investigated experimentally. When the barrier thickness decreases from 20 to 10 nm, the photoluminescence intensity at room temperature increases, which can be attributed to the reduced polarization field in the thin-barrier sample. However, with a further reduction in the thickness to 5 nm, the sample’s luminescence intensity decreases significantly. It is found that the strong nonradiative loss process induced by the deteriorated crystal quality and the quantum-tunneling-assisted leakage of carriers may jointly contribute to the enhanced nonradiative loss of photogenerated electrons and holes, leading to a significant reduction in photoluminescence intensity of the sample with nanoscale ultrathin GaN quantum barriers. Full article

(This article belongs to the Special Issue Advances in GaN-Based Optoelectronic Materials and Devices)

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11 pages, 2045 KB

Open AccessEditor’s ChoiceArticle

Superfluorescence of Sub-Band States in C-Plane In_0.1Ga_0.9N/GaN Multiple-QWs

by Cairong Ding, Zesheng Lv, Xueran Zeng and Baijun Zhang

Nanomaterials 2022, 12(3), 327; https://doi.org/10.3390/nano12030327 - 20 Jan 2022

Cited by 1 | Viewed by 2346

Abstract

Superfluorescence is a collective emission from quantum coherent emitters due to quantum fluctuations. This is characterized by the existence of the delay time (

τ_{D})

for the emitters coupling and phase-synchronizing to each other spontaneously. Here we report the observation of [...] Read more.

Superfluorescence is a collective emission from quantum coherent emitters due to quantum fluctuations. This is characterized by the existence of the delay time (

τ_{D})

for the emitters coupling and phase-synchronizing to each other spontaneously. Here we report the observation of superfluorescence in c-plane In_0.1Ga_0.9N/GaN multiple-quantum wells by time-integrated and time-resolved photoluminescence spectroscopy under higher excitation fluences of the 267 nm laser and at room temperature, showing a characteristic

τ_{D}

from 79 ps to 62 ps and the ultrafast radiative decay (7.5 ps) after a burst of photons. Time-resolved traces present a small quantum oscillation from coupled In_0.1Ga_0.9N/GaN multiple-quantum wells. The superfluorescence is attributed to the radiative recombination of coherent emitters distributing on strongly localized subband states, E_e₁→E_hh₁ or E_e₁→E_lh₁ in 3nm width multiple-quantum wells. Our work paves the way for deepening the understanding of the emission mechanism in the In_0.1Ga_0.9N/GaN quantum well at a higher injected carrier density. Full article

(This article belongs to the Special Issue Advanced Nanocomposites for Photonics and Optoelectronics and Mechanics)

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9 pages, 3713 KB

Open AccessArticle

Optical Properties of InGaN/GaN QW with the Same Well-Plus-Barrier Thickness

by Huan Xu, Xin Hou, Lan Chen, Yang Mei and Baoping Zhang

Crystals 2022, 12(1), 114; https://doi.org/10.3390/cryst12010114 - 15 Jan 2022

Cited by 6 | Viewed by 3150

Abstract

Optical properties of wurtzite violet InGaN/GaN quantum well (QW) structures, with the same well-plus-barrier thickness, grown by metal-organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates, were investigated using temperature-dependent photoluminescence (TDPL) and excitation-power-dependent photoluminescence (PDPL). Two samples were compared: one had a [...] Read more.

Optical properties of wurtzite violet InGaN/GaN quantum well (QW) structures, with the same well-plus-barrier thickness, grown by metal-organic chemical vapor deposition (MOCVD) on c-plane sapphire substrates, were investigated using temperature-dependent photoluminescence (TDPL) and excitation-power-dependent photoluminescence (PDPL). Two samples were compared: one had a thicker well (InGaN/GaN 3/5 nm); the other had a thicker barrier (InGaN/GaN 2/6 nm). It was found that the GaN barrier thickness in the InGaN/GaN MQWs plays an important role in determining the optical characteristics of the MQWs. The peak energy of the two samples varied with temperature in an S-shape. The thicker-barrier sample had a higher turning point from blueshift to redshift, indicating a stronger localization effect. From the Arrhenius plot of the normalized integrated PL intensity, it was found that the activation energy of the nonradiative process also increased with a thicker barrier thickness. The radiation recombination process was dominated in the sample of the thicker barrier, while the non-radiation process cannot be negligible in the sample of the thicker well. Full article

(This article belongs to the Special Issue Advances in GaN-Based Optoelectronic Materials and Devices)

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7 pages, 2483 KB

Open AccessArticle

Enhanced Optoelectronic Performance of Yellow Light-Emitting Diodes Grown on InGaN/GaN Pre-Well Structure

by Xiaoyu Zhao, Zehong Wan, Liyan Gong, Guoyi Tao and Shengjun Zhou

Nanomaterials 2021, 11(12), 3231; https://doi.org/10.3390/nano11123231 - 28 Nov 2021

Cited by 16 | Viewed by 3442

Abstract

InGaN-based long-wavelength light-emitting diodes (LEDs) are indispensable components for the next-generation solid-state lighting industry. In this work, we introduce additional InGaN/GaN pre-wells in LED structure and investigate the influence on optoelectronic properties of yellow (~575 nm) LEDs. It is found that yellow LED [...] Read more.

InGaN-based long-wavelength light-emitting diodes (LEDs) are indispensable components for the next-generation solid-state lighting industry. In this work, we introduce additional InGaN/GaN pre-wells in LED structure and investigate the influence on optoelectronic properties of yellow (~575 nm) LEDs. It is found that yellow LED with pre-wells exhibits a smaller blue shift, and a 2.2-fold increase in light output power and stronger photoluminescence (PL) intensity compared to yellow LED without pre-wells. The underlying mechanism is revealed by using Raman spectra, temperature-dependent PL, and X-ray diffraction. Benefiting from the pre-well structure, in-plane compressive stress is reduced, which effectively suppresses the quantum confined stark effect. Furthermore, the increased quantum efficiency is also related to deeper localized states with reduced non-radiative centers forming in multiple quantum wells grown on pre-wells. Our work demonstrates a comprehensive understanding of a pre-well structure for obtaining efficient LEDs towards long wavelengths. Full article

(This article belongs to the Special Issue III-N Based Semiconductor Nanomaterials for Photonic and Electronic Devices)

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9 pages, 2211 KB

Open AccessArticle

Optical Properties of GaN-Based Green Light-Emitting Diodes Influenced by Low-Temperature p-GaN Layer

by Jianfei Li, Duo Chen, Kuilong Li, Qiang Wang, Mengyao Shi, Dejie Diao, Chen Cheng, Changfu Li and Jiancai Leng

Nanomaterials 2021, 11(11), 3134; https://doi.org/10.3390/nano11113134 - 20 Nov 2021

Cited by 4 | Viewed by 3043

Abstract

GaN-based green light-emitting diodes (LEDs) with different thicknesses of the low-temperature (LT) p-GaN layer between the last GaN barriers and p-AlGaN electron blocking layer were characterized by photoluminescence (PL) and electroluminescence (EL) spectroscopic methods in the temperature range of 6–300 K and injection [...] Read more.

GaN-based green light-emitting diodes (LEDs) with different thicknesses of the low-temperature (LT) p-GaN layer between the last GaN barriers and p-AlGaN electron blocking layer were characterized by photoluminescence (PL) and electroluminescence (EL) spectroscopic methods in the temperature range of 6–300 K and injection current range of 0.01–350 mA. Based on the results, we suggest that a 20 nm-thick LT p-GaN layer can effectively prevent indium (In) re-evaporation, improve the quantum-confined Stark effect in the last quantum well (QW) of the active region, and finally reduce the efficiency droop by about 7%. Full article

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12 pages, 3462 KB

Open AccessArticle

32 × 32 Pixelated High-Power Flip-Chip Blue Micro-LED-on-HFET Arrays for Submarine Optical Communication

by Tae Kyoung Kim, Abu Bashar Mohammad Hamidul Islam, Yu-Jung Cha and Joon Seop Kwak

Nanomaterials 2021, 11(11), 3045; https://doi.org/10.3390/nano11113045 - 12 Nov 2021

Cited by 8 | Viewed by 3455

Abstract

This work proposes the use of integrated high-power InGaN/GaN multiple-quantum-well flip-chip blue micro light-emitting diode (μ-LED) arrays on an AlGaN/GaN-based heterojunction field-effect transistor (HFET), also known as a high electron mobility transistor (HEMT), for various applications: underwater wireless optical communication (UWOC) and smart [...] Read more.

This work proposes the use of integrated high-power InGaN/GaN multiple-quantum-well flip-chip blue micro light-emitting diode (μ-LED) arrays on an AlGaN/GaN-based heterojunction field-effect transistor (HFET), also known as a high electron mobility transistor (HEMT), for various applications: underwater wireless optical communication (UWOC) and smart lighting. Therefore, we demonstrate high-power μ-LED-on-HEMT arrays that consist of 32 × 32 pixelated μ-LED arrays and 32 × 32 pixelated HEMT arrays and that are interconnected by a solder bump bonding technique. Each pixel of the μ-LED arrays emits light in the HEMT on-state. The threshold voltage, the off-state leakage current, and the drain current of the HEMT arrays are −4.6 V, <~1.1 × 10⁻⁹ A at gate-to-source voltage (V_GS) = −10 V, and 21 mA at V_GS = 4 V, respectively. At 12 mA, the forward voltage and the light output power (LOP) of μ-LED arrays are ~4.05 V and ~3.5 mW, respectively. The LOP of the integrated μ-LED-on-HEMT arrays increases from 0 to ~4 mW as the V_GS increases from −6 to 4 V at V_DD = 10 V. Each pixel of the integrated μ-LEDs exhibits a modulated high LOP at a peak wavelength of ~450 nm, showing their potential as candidates for use in UWOC. Full article

(This article belongs to the Special Issue III-N Based Semiconductor Nanomaterials for Photonic and Electronic Devices)

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