Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate
This study investigates polarization-dependent light extraction efficiency (<italic>η</italic><sub>extraction </sub>) of AlGaN-based flip-chip ultraviolet (UV) light-emitting diodes (LEDs) emitting at 230 nm and 280 nm with microdome-shaped patterning on...
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2018-01-01
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| Series: | IEEE Photonics Journal |
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| Online Access: | https://ieeexplore.ieee.org/document/8384025/ |
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| author | Yu Kee Ooi Jing Zhang |
| author_facet | Yu Kee Ooi Jing Zhang |
| author_sort | Yu Kee Ooi |
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| description | This study investigates polarization-dependent light extraction efficiency (<italic>η</italic><sub>extraction </sub>) of AlGaN-based flip-chip ultraviolet (UV) light-emitting diodes (LEDs) emitting at 230 nm and 280 nm with microdome-shaped patterning on sapphire substrate based on 3-D finite-difference time-domain simulations. Three types of patterned sapphire substrates (PSS) have been analyzed: bottom-side PSS, top-side PSS, and double-sided PSS. Our results show that microdome-shaped patterning on sapphire substrate is predominantly beneficial in enhancing transverse-magnetic (TM)-polarized output. Specifically, TM-polarized <italic>η</italic><sub>extraction</sub> enhancement of up to ∼4.5 times and ∼2.2 times can be obtained for 230 nm and 280 nm UV LEDs with bottom-side PSS, respectively, and ∼6.3 times and ∼1.8 times for 230 nm and 280 nm UV LEDs with top-side PSS, respectively. By employing double-sided PSS, up to ∼11.2 times and ∼2.6 times enhancement in TM-polarized <italic>η</italic><sub>extraction</sub> can be achieved for 230 nm and 280 nm UV LEDs, respectively. In contrast, the microdome-shaped PSS act as a reflector for transverse-electric-polarized photons which leads to severe limitation in light extraction for both 230 nm and 280 nm flip-chip UV LEDs. Thus, it is expected that this study will serve as a guidance in designing PSS for high-efficiency mid- and deep-UV LEDs. |
| format | Article |
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| institution | Matheson Library |
| issn | 1943-0655 |
| language | English |
| publishDate | 2018-01-01 |
| publisher | IEEE |
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| series | IEEE Photonics Journal |
| spelling | doaj-art-d2798b47aad6487489e9b74d97b85e9f2025-07-01T23:40:31ZengIEEEIEEE Photonics Journal1943-06552018-01-0110411310.1109/JPHOT.2018.28472268384025Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire SubstrateYu Kee Ooi0https://orcid.org/0000-0003-1793-2085Jing Zhang1https://orcid.org/0000-0002-9225-4360Microsystems Engineering, Rochester Institute of Technology, Rochester, NY, USAMicrosystems Engineering, Rochester Institute of Technology, Rochester, NY, USAThis study investigates polarization-dependent light extraction efficiency (<italic>η</italic><sub>extraction </sub>) of AlGaN-based flip-chip ultraviolet (UV) light-emitting diodes (LEDs) emitting at 230 nm and 280 nm with microdome-shaped patterning on sapphire substrate based on 3-D finite-difference time-domain simulations. Three types of patterned sapphire substrates (PSS) have been analyzed: bottom-side PSS, top-side PSS, and double-sided PSS. Our results show that microdome-shaped patterning on sapphire substrate is predominantly beneficial in enhancing transverse-magnetic (TM)-polarized output. Specifically, TM-polarized <italic>η</italic><sub>extraction</sub> enhancement of up to ∼4.5 times and ∼2.2 times can be obtained for 230 nm and 280 nm UV LEDs with bottom-side PSS, respectively, and ∼6.3 times and ∼1.8 times for 230 nm and 280 nm UV LEDs with top-side PSS, respectively. By employing double-sided PSS, up to ∼11.2 times and ∼2.6 times enhancement in TM-polarized <italic>η</italic><sub>extraction</sub> can be achieved for 230 nm and 280 nm UV LEDs, respectively. In contrast, the microdome-shaped PSS act as a reflector for transverse-electric-polarized photons which leads to severe limitation in light extraction for both 230 nm and 280 nm flip-chip UV LEDs. Thus, it is expected that this study will serve as a guidance in designing PSS for high-efficiency mid- and deep-UV LEDs.https://ieeexplore.ieee.org/document/8384025/Patterned sapphire substratepolarization-dependent light extraction efficiencyquantum well structureultraviolet light-emitting diodes. |
| spellingShingle | Yu Kee Ooi Jing Zhang Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate IEEE Photonics Journal Patterned sapphire substrate polarization-dependent light extraction efficiency quantum well structure ultraviolet light-emitting diodes. |
| title | Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate |
| title_full | Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate |
| title_fullStr | Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate |
| title_full_unstemmed | Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate |
| title_short | Light Extraction Efficiency Analysis of Flip-Chip Ultraviolet Light-Emitting Diodes With Patterned Sapphire Substrate |
| title_sort | light extraction efficiency analysis of flip chip ultraviolet light emitting diodes with patterned sapphire substrate |
| topic | Patterned sapphire substrate polarization-dependent light extraction efficiency quantum well structure ultraviolet light-emitting diodes. |
| url | https://ieeexplore.ieee.org/document/8384025/ |
| work_keys_str_mv | AT yukeeooi lightextractionefficiencyanalysisofflipchipultravioletlightemittingdiodeswithpatternedsapphiresubstrate AT jingzhang lightextractionefficiencyanalysisofflipchipultravioletlightemittingdiodeswithpatternedsapphiresubstrate |