Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes

Chia Yen Huang; Chia Lung Tsai; Cheng Yao Huang; Rong Yu Yang; Yewchung Sermon Wu; Hung Wei Yen; Yi Keng Fu

doi:10.1063/5.0037588

Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes

Chia Yen Huang^*, Chia Lung Tsai, Cheng Yao Huang, Rong Yu Yang, Yewchung Sermon Wu, Hung Wei Yen, Yi Keng Fu

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

UVC light-emitting diodes (LEDs, λ = 275 nm) with different types of contact layers and sapphire substrates were demonstrated on high-quality AlN templates. For LEDs on flat sapphire substrates (FSSs), replacing the absorbing p-GaN contact with p-AlGaN short-period superlattices (p-SPSLs) strongly enhanced the emission along the substrate normal. The integrated external quantum efficiency (EQE) increased from 2.4% to 3.9% under I = 350 mA. For LEDs with a p-SPSL contact, replacing the FSS with nano-patterned sapphire substrates slightly deteriorated the quality of epitaxy, but the overall EQE is still enhanced to 4.4% under I > 350 mA without lens encapsulation. According to the far-field intensity measurement, the light extraction is better improved along the high emission angle to the substrate normal. The interplay among substrates, dipole polarization, and EQE enhancement factors was further analyzed and discussed in the context.

Original language	English
Article number	261102
Journal	Applied Physics Letters
Volume	117
Issue number	26
DOIs	https://doi.org/10.1063/5.0037588
State	Published - 28 Dec 2020

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@article{84105bb5af67439fb39866371fa2aaa3,

title = "Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes",

abstract = "UVC light-emitting diodes (LEDs, λ = 275 nm) with different types of contact layers and sapphire substrates were demonstrated on high-quality AlN templates. For LEDs on flat sapphire substrates (FSSs), replacing the absorbing p-GaN contact with p-AlGaN short-period superlattices (p-SPSLs) strongly enhanced the emission along the substrate normal. The integrated external quantum efficiency (EQE) increased from 2.4% to 3.9% under I = 350 mA. For LEDs with a p-SPSL contact, replacing the FSS with nano-patterned sapphire substrates slightly deteriorated the quality of epitaxy, but the overall EQE is still enhanced to 4.4% under I > 350 mA without lens encapsulation. According to the far-field intensity measurement, the light extraction is better improved along the high emission angle to the substrate normal. The interplay among substrates, dipole polarization, and EQE enhancement factors was further analyzed and discussed in the context. ",

author = "Huang, {Chia Yen} and Tsai, {Chia Lung} and Huang, {Cheng Yao} and Yang, {Rong Yu} and Wu, {Yewchung Sermon} and Yen, {Hung Wei} and Fu, {Yi Keng}",

note = "Publisher Copyright: {\textcopyright} 2020 Author(s).",

year = "2020",

month = dec,

day = "28",

doi = "10.1063/5.0037588",

language = "English",

volume = "117",

journal = "Applied Physics Letters",

issn = "0003-6951",

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T1 - Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes

AU - Huang, Chia Yen

AU - Tsai, Chia Lung

AU - Huang, Cheng Yao

AU - Yang, Rong Yu

AU - Wu, Yewchung Sermon

AU - Yen, Hung Wei

AU - Fu, Yi Keng

PY - 2020/12/28

Y1 - 2020/12/28

N2 - UVC light-emitting diodes (LEDs, λ = 275 nm) with different types of contact layers and sapphire substrates were demonstrated on high-quality AlN templates. For LEDs on flat sapphire substrates (FSSs), replacing the absorbing p-GaN contact with p-AlGaN short-period superlattices (p-SPSLs) strongly enhanced the emission along the substrate normal. The integrated external quantum efficiency (EQE) increased from 2.4% to 3.9% under I = 350 mA. For LEDs with a p-SPSL contact, replacing the FSS with nano-patterned sapphire substrates slightly deteriorated the quality of epitaxy, but the overall EQE is still enhanced to 4.4% under I > 350 mA without lens encapsulation. According to the far-field intensity measurement, the light extraction is better improved along the high emission angle to the substrate normal. The interplay among substrates, dipole polarization, and EQE enhancement factors was further analyzed and discussed in the context.

AB - UVC light-emitting diodes (LEDs, λ = 275 nm) with different types of contact layers and sapphire substrates were demonstrated on high-quality AlN templates. For LEDs on flat sapphire substrates (FSSs), replacing the absorbing p-GaN contact with p-AlGaN short-period superlattices (p-SPSLs) strongly enhanced the emission along the substrate normal. The integrated external quantum efficiency (EQE) increased from 2.4% to 3.9% under I = 350 mA. For LEDs with a p-SPSL contact, replacing the FSS with nano-patterned sapphire substrates slightly deteriorated the quality of epitaxy, but the overall EQE is still enhanced to 4.4% under I > 350 mA without lens encapsulation. According to the far-field intensity measurement, the light extraction is better improved along the high emission angle to the substrate normal. The interplay among substrates, dipole polarization, and EQE enhancement factors was further analyzed and discussed in the context.

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DO - 10.1063/5.0037588

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VL - 117

JO - Applied Physics Letters

JF - Applied Physics Letters

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ER -

Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes

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