Improvement in Light Output of Ultraviolet Light-Emitting Diodes with Patterned Double-Layer ITO by Laser Direct Writing

A patterned double-layer indium-tin oxide (ITO), including the first unpatterned ITO layer serving as current spreading and the second patterned ITO layer serving as light extracting, was applied to obtain uniform current spreading and high light extraction efficiency (LEE) of GaN-based ultraviolet (UV) light-emitting diodes (LEDs). Periodic pinhole patterns were formed on the second ITO layer by laser direct writing to increase the LEE of UV LED. Effects of interval of pinhole patterns on optical and electrical properties of UV LED with patterned double-layer ITO were studied by numerical simulations and experimental investigations. Due to scattering out of waveguided light trapped inside the GaN film, LEE of UV LED with patterned double-layer ITO was improved as compared to UV LED with planar double-layer ITO. As interval of pinhole patterns decreased, the light output power (LOP) of UV LED with patterned double-layer ITO increased. In addition, UV LED with patterned double-layer ITO exhibited a slight degradation of current spreading as compared to the UV LED with a planar double-layer ITO. The forward voltage of UV LED with patterned double-layer ITO increased as the interval of pinhole patterns decreased.

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Nanostructural Effect of ZnO on Light Extraction Efficiency of Near-Ultraviolet Light-Emitting Diodes

Journal of Nanomaterials ◽

10.1155/2016/7947623 ◽

2016 ◽

Vol 2016 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Young Jae Park ◽

Hyounsuk Song ◽

Kang Bok Ko ◽

Beo Deul Ryu ◽

Tran Viet Cuong ◽

...

Keyword(s):

Ultraviolet Light ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Light Output ◽

Light Extraction Efficiency ◽

Zno Nanostructures ◽

Light Emitting ◽

Near Ultraviolet ◽

Output Efficiency ◽

Ultraviolet Light Emitting Diodes

The effect of ZnO nanostructures on the light output power of 375 nm near-ultraviolet light-emitting diodes (NUV-LEDs) was investigated by comparing one-dimensional (1D) nanorods (NR-ZnO) with two-dimensional (2D) nanosheets (NS-ZnO). ZnO nanostructures were grown on a planar indium tin oxide (ITO) by solution based method at low temperature of 90°C without degradation of the forward voltage. At an injection current of 100 mA, the light output efficiency of NUV-LED with NR-ZnO was enhanced by around 30% compared to the conventional NUV-LEDs without ZnO nanostructures. This improvement is due to the formation of a surface texturing, resulting in a larger escape cone and a multiple scattering for the photons in the NUV-LED, whereas the light output efficiency of NUV-LED with NS-ZnO was lower than that of the conventional NUV-LEDs due to the internal reflection and light absorption in the defective sites of NS-ZnO.

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Light Output Enhancement of InGaN/GaN Light-Emitting Diodes with Contrasting Indium Tin-Oxide Nanopatterned Structures

Journal of Nanomaterials ◽

10.1155/2013/832170 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Sang Hyun Jung ◽

Keun Man Song ◽

Young Su Choi ◽

Hyeong-Ho Park ◽

Hyun-Beom Shin ◽

...

Keyword(s):

Circular Hole ◽

Tin Oxide ◽

Indium Tin Oxide ◽

Inductively Coupled Plasma ◽

Light Emitting Diodes ◽

Hexagonal Lattice ◽

Light Output ◽

Light Extraction Efficiency ◽

Output Intensity ◽

Light Emitting

Various nanopatterns on the transparent conducting indium tin oxide (ITO) layer are investigated to enhance the light extraction efficiency of the InGaN/GaN light-emitting diodes (LEDs). Triangular, square, and circular nanohole patterns with the square and hexagonal lattices are fabricated on the ITO layer by an electron beam lithography and inductively coupled plasma dry etching processes. The circular hole pattern with a hexagonal geometry is found to be the most effective among the studied structures. Light output intensity measurements reveal that the circular hole nanopatterned ITO LEDs with a hexagonal lattice show up to 35.6% enhancement of output intensity compared to the sample without nanopatterns.

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Enhanced light output power of near UV light emitting diodes with graphene / indium tin oxide nanodot nodes for transparent and current spreading electrode

Optics Express ◽

10.1364/oe.19.023111 ◽

2011 ◽

Vol 19 (23) ◽

pp. 23111 ◽

Cited By ~ 27

Author(s):

Tae Hoon Seo ◽

Kang Jea Lee ◽

Ah Hyun Park ◽

Chang-Hee Hong ◽

Eun-Kyung Suh ◽

...

Keyword(s):

Output Power ◽

Tin Oxide ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Uv Light ◽

Light Output ◽

Light Output Power ◽

Current Spreading ◽

Light Emitting

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Performance of GaN-Based LEDs with Nanopatterned Indium Tin Oxide Electrode

Journal of Nanomaterials ◽

10.1155/2016/8202405 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7

Author(s):

Zhanxu Chen ◽

Wenjie Liu ◽

Wei Wan ◽

Gengyan Chen ◽

Yongzhu Chen ◽

...

Keyword(s):

Tin Oxide ◽

Indium Tin Oxide ◽

Ohmic Contacts ◽

Three Dimensional ◽

Light Output ◽

Light Extraction Efficiency ◽

Experimental Result ◽

Indium Tin Oxide Electrode ◽

Light Emitting ◽

Ito Electrode

The indium tin oxide (ITO) has been widely applied in light emitting diodes (LEDs) as the transparent current spreading layer. In this work, the performance of GaN-based blue light LEDs with nanopatterned ITO electrode is investigated. Periodic nanopillar ITO arrays are fabricated by inductive coupled plasma etching with the mask of polystyrene nanosphere. The light extraction efficiency (LEE) of LEDs can be improved by nanopatterned ITO ohmic contacts. The light output intensity of the fabricated LEDs with nanopatterned ITO electrode is 17% higher than that of the conventional LEDs at an injection current of 100 mA. Three-dimensional finite difference time domain simulation matches well with the experimental result. This method may serve as a practical approach to improving the LEE of the LEDs.

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Improved light extraction efficiency of GaN-based light emitting diodes by using needle-shape indium tin oxide p-contact

physica status solidi (c) ◽

10.1002/pssc.200778439 ◽

2008 ◽

Vol 5 (6) ◽

pp. 2083-2085 ◽

Cited By ~ 6

Author(s):

Fumio Ishida ◽

Kazumasa Yoshimura ◽

Katsuyuki Hoshino ◽

Kazuyuki Tadatomo

Keyword(s):

Tin Oxide ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Extraction Efficiency ◽

Light Extraction ◽

Light Extraction Efficiency ◽

Light Emitting

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High-Power GaN-Based Vertical Light-Emitting Diodes on 4-Inch Silicon Substrate

Nanomaterials ◽

10.3390/nano9081178 ◽

2019 ◽

Vol 9 (8) ◽

pp. 1178 ◽

Cited By ~ 2

Author(s):

Qiang Zhao ◽

Jiahao Miao ◽

Shengjun Zhou ◽

Chengqun Gui ◽

Bin Tang ◽

...

Keyword(s):

High Power ◽

Silicon Substrate ◽

Flip Chip ◽

Heat Dissipation ◽

Light Emitting Diodes ◽

Light Output ◽

Current Spreading ◽

Light Emitting ◽

Fabry Perot ◽

Lift Off

We demonstrate high-power GaN-based vertical light-emitting diodes (LEDs) (VLEDs) on a 4-inch silicon substrate and flip-chip LEDs on a sapphire substrate. The GaN-based VLEDs were transferred onto the silicon substrate by using the Au–In eutectic bonding technique in combination with the laser lift-off (LLO) process. The silicon substrate with high thermal conductivity can provide a satisfactory path for heat dissipation of VLEDs. The nitrogen polar n-GaN surface was textured by KOH solution, which not only improved light extract efficiency (LEE) but also broke down Fabry–Pérot interference in VLEDs. As a result, a near Lambertian emission pattern was obtained in a VLED. To improve current spreading, the ring-shaped n-electrode was uniformly distributed over the entire VLED. Our combined numerical and experimental results revealed that the VLED exhibited superior heat dissipation and current spreading performance over a flip-chip LED (FCLED). As a result, under 350 mA injection current, the forward voltage of the VLED was 0.36 V lower than that of the FCLED, while the light output power (LOP) of the VLED was 3.7% higher than that of the FCLED. The LOP of the FCLED saturated at 1280 mA, but the light output saturation did not appear in the VLED.

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Enhanced Optical Output of Near-Ultraviolet Light-Emitting Diodes by a Monolayer of Nanospheres

Journal of Nanomaterials ◽

10.1155/2020/5147543 ◽

2020 ◽

Vol 2020 ◽

pp. 1-7

Author(s):

Wei Wan ◽

Zhanxu Chen ◽

Yongzhu Chen ◽

Gengyan Chen

Keyword(s):

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Low Cost ◽

Incident Light ◽

Light Extraction Efficiency ◽

Light Emitting ◽

Hexagonal Close Packed ◽

Exit Surface ◽

Near Ultraviolet ◽

Optical Output

The optical output of near-ultraviolet (NUV) light-emitting diodes (LEDs) was improved by including a monolayer of hexagonal close-packed polystyrene (PS) nanospheres. PS nanospheres with different sizes were deposited on the indium tin oxide layer of the NUV LEDs. The electroluminescence results showed that the light extraction efficiency of the NUV LEDs was increased by the inclusion of PS nanospheres, and the maximum optical output enhancement was obtained when the size of the nanospheres was close to the light wavelength. The largest enhancement of the optical output of 1.27-fold was obtained at an injection current of 100 mA. The enhanced optical output was attributed to part of the incident light beyond the critical angle being extracted when the exit surface of the NUV LEDs had a PS nanosphere monolayer. This method may serve as a low-cost and effective approach to raise the efficiency of NUV LEDs.

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