Nano-imprinting of refractive-index-matched indium tin oxide sol–gel in light-emitting diodes for eliminating total internal reflection

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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Study on Light Intensity Enhancement of ZnO/ITO/P-GaN Light-Emitting Diodes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.4084 ◽

2011 ◽

Vol 130-134 ◽

pp. 4084-4087

Author(s):

Hsing Cheng Chang ◽

Ya Hui Chen ◽

San Shan Hung ◽

Chi Chih Lai ◽

Chein Chuan Hung ◽

...

Keyword(s):

Light Intensity ◽

Indium Tin Oxide ◽

Light Emitting Diodes ◽

Zno Nanorods ◽

Light Output ◽

Surface Roughening ◽

Light Emitting ◽

Intensity Enhancement ◽

Great Performance ◽

Output Efficiency

Light intensity enhancement of GaN-based blue light-emitting diodes (LEDs) is performed using different surface roughening technologies. Three roughening technologies are applied that contain surface roughening of p-GaN, textured indium tin oxide (ITO) on roughened p-GaN, and growing ZnO nanorods on textured ITO/p-GaN. A roughened p-GaN surface was grown on the c-plane sapphire substrate at temperature 800 °C. The morphologies of the textured LEDs with roughness in the range from 9.67 nm to 51.13 nm were observed. The light output efficiency of LED with roughened ITO layer is increased up to 73.8 %. Different dimensions of LEDs can be driven by constant injection current 20 mA without increasing threshold voltage, and larger size of ZnO/ITO/p-GaN LED shows higher luminance intensity. The LEDs with ZnO nanorods on roughened ITO/GaN have shown great performance to enhance the power conversion efficiency.

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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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