Post on 09-Oct-2020
UV LEDs的終端新應用
Genesis Photonics, Inc. 新世紀光電R&D center 研發中心Cheng-Yen Robert Chen, Ph. D.陳正言博士2013/09/04
Outline
¤Introduction to UV applications
¤Development Status of UV LEDs
¤Photoinitiated polymerization for UV LED active packaging and waveguide devices
¤Summary
UV Spectrum Range
• UVA能透入皮膚深部,氧化黑色素物質,使皮膚黑化,增強抵抗,也會導致黑色素瘤(Melanoma)。
• UVB可促進皮膚生成維生素D,引發皮膚下血管擴張,增加血流量,造成血管亢進發紅,進而成紅斑,脫皮、甚而發炎等。
• UVC有強烈的殺菌能力,破壤細胞DNA,可造成皮膚病變,灼傷眼角膜等。
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X-ray UV Visible Infrared
List of UV Applications
• 230 to 400 nm: optical sensors and instrumentation• 240 to 280 nm: sterilization of surface areas and water• 250 to 405 nm: forensic and bodily fluid detection and analysis• 260 to 300 nm: DNA/RNA/protein analysis, drug discovery• 300 to 320 nm: medical light therapy• 365 to 400 nm: polymer and ink printing• 375 to 395 nm: counterfeit detection• 390 to 410 nm: superficial/cosmetic sterilization
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Source: http://electronicdesign.com/energy/
•治療乾癬 (311nm),白斑,濕疹
Intensity-dependent UV applications
UV-C
UV-A
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Nitride UVLEDs
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3.1 3.2 3.3 3.4 3.5
1
2
3
4
5
6
1
2
3
4
5
6
InN
GaN
AlN
ZnO
Band
gap
Ener
gy (e
V)
Lattice Constant (Å)
Bandgap Energy vs. Lattice Constant
400nm
200nm
UV-B
AlGaInN LEDs can cover UVA, UVB and UVC spectral range
Benefit of UV LEDs• Compactness• Robustness• low cost of ownership (system level)• Environmentally-friendly composition
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Nichia
Luminus Devices
GPI SemiLEDs Crystal IS
UV LED business with 43% CAGR from 2012 to 2017
Source: UV LEDs report, March 2013, Yole Dévelopement
Development Status of UV LEDs
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Development of UV LEDs
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Source: http://www.i-micronews.com/Upload/iLED/iLED_June2013_IR.pdf
• 1st- UVA for Printing• 2nd- UVA for Curing• 3rd- UV-B and UV-C applications
Performance Improvement of UV LED @ 395nm
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> 20x improvement for the last decade
600mw
250mw
330mw
UVA LED Development in GPI
2009 2010 2011 2012 2013 201450
100
150
200
250
300
350
400
450
500
550
600
650
405nm 385nm 375nm
Die : 1x1 mm2
mW : GPI PKG Lamp @ 350mA
Rad
ial f
lux
(mW
)
Year
365nm
Hot (85oC)/Cold(25oC) factor of UVA LEDs
0 20 40 60 80 100 120 140
40
50
60
70
80
90
380nm 405nm 450nm
Hot
/Col
d Fa
ctor
(%)
Current Density (A/cm2)
ü Unlike blue InGaN LEDs, UV LEDs exist higher hot/cold factor at higher operation current density.
ü May be suitable for flip-chip design.
GPI flip chips- AT LED
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ü Higher power density (W/cm2)ü Better reliabilityü Better thermal conductivityü Overdrive capability
Benefits of flip chips
GPI UV flip-chip LED
• Deliver more than 2000 mW/cm2 (390nm) in working distance• Lifetime > 20000 hrs• Operate at more than 100W
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Module5050: 4*4(64ea of 45mil dies)
25mm
25mm
陶瓷基板
PCB板
(Top view)
Nail Gel UVA curing System
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ü Wavelength: 390 to 410nmü 45mil flip chip operated @ 700mA to 1Aü Curing time: within 30 seconds
Development of UVC LEDs
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UV-C Applications
• Germicidal Disinfection• Water Purification• Surface Sterilization• Air Purification• Analytical Instrumentation, Emitters• Protein Analysis, DNA Sequencing, Drug Discovery• Forensic Analysis• Optical Sensing• Ozone Monitoring
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λ
Absorption
260nm 280nm
DNA/RNA
protein
Comparison of UVC LED with Mercury lamp and Xenon lamp
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Source:http://www.cisuvc.com
EQE from 10% to >50%l AlInGaP Red LED : 1988à2000 (12 years)l InGaN Blue LED : 1998à2007 (9 years)l AlInGaN DUV LED : 2012à2020 (8 years or less) ??
LED history from Red to DUV
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Source: Hideki Hirayama (RIKEN) report in “LED 50 YEARS”
Evolution of UV-C LED Performance-by RIKEN, Japan
Evolution of UV-C LED Performance-by RIKEN, Japan
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Source: Hideki Hirayama (RIKEN) report in “LED 50 YEARS”
A commercial UVB LED
2013/3
Al2O3
AlxGa1-xN (8μm)
AlN/AlGaN SLS
AlGaN/AlGaN SLS
AlxGa1-xN (0.3μm)
AlxGa1-xN (0.4μm)
AlN buffer (2.4 μm)
ü The epitaxial structure is quite different from InGaN blue LEDs.
ü Much larger forward voltage remain space of improvement.
120mw 90mw 13mw 1mw
EE=75% IQE X EE=15% LEE=8%
WPE=0.8%
Commercial 275nm LED performance
l (1) Dislocation reduction (IQE)Ø quality of AlN on sapphireà TD ~2~3 E8 /cm2 , (0 0 2)=190 arsec , (1 0 2)=300 arsecØ n-AlGaN Al=60% à (0 0 2)=307 arsecØ MQWà IQE > 50%
l (2) Reduction of optical loss (LEE)Ø high absorption in p-layer à p-AlGaN/AlGaN SL 60% Transmission @275nmØ low contact reflection in DUV à p-pad R=70% , n-pad R=50% @275nmØ lack of encapsulation à surface roughing & encapsulated
l Summary Ø LEE > 25% ,IQE>50% à EQE>11% , WPE>7%
EQE breakdown
Highlights of some UVC LED Performance
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Company Wp IQE LEE EQE WPE
UV Craftly Co. Ltd 285nm >80% 15%14.3%(peak)>10% (normal) ---
SETI 275nm 55% >25% 11% 7%
Meijo Univ. ~365nm 29% 11.4% 3.4% 2.6%
Berlin Technical Univ. 305nm 23% 4.5% 0.5%
Crystal IS270nm260nm 70% 15%
8.2%@100mA6.5%@65mA
4.5%4.9%
(Data updated in 2012)
ü IQE depends on high quality AlxGa1-xN material & structure design.
ü LEE is very important for DUV development , including material absorption & chip reflectance process.
ü Thermal decay , burn in decay , lifetime decay also need to be considered seriously.
Brief Summary
Photoinitiated polymerization for UV LED active packaging and waveguide devices
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Blue LED active packing method with photosensitive polymerization
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Ref: 17 March 2008 / Vol. 16, No. 6 / OPTICS EXPRESS, 3680
An optical curing process
Chain reaction of photo-induced polymerization
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GPI collaboration with National Taiwan University
Simulation of UV propagation
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Simulation Results
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Constant LED power Constant exposure time
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Experimental results
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GPI collaboration with National Taiwan University
ü Suitable for flip chips (no wire bonding)ü mm-scale optical lensü Control of LED radiation pattern through UV exposure conditions
UV-induced photo-initiated polymerization for self-written waveguides
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X-type waveguide
Y-type waveguide
Simulation Results
ü Combining with automation control, similar to 3D printing technology, complex optical coupling devices could be fabricated.
Summary
• With outstanding properties, UV LEDs provides versatile application possibilities.
• Applications of UVA LEDs in printing and curing industry are increasing firmly.
• The population of UVB/UVC LED applications depends strongly on the performance improvement of UV LEDs.
• Novel applications of UV LEDs are expected to come along with LED technology breakthrough.
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