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Lighting Your Path to the Future
IMAPS Global Business Council November 14, 2007
M. George Craford, CTO Philips Lumileds Lighting Company
2Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Outline
Buckingham Palace, London, England
Lit by LUXEON LEDs
• Power LED Technology Status and Trends
• Existing and Emerging Applications
• Challenges and Recent Developments for Solid State Lighting
3Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
• Emerging ~ 100 lm/W phosphor white power LEDs • Expect ~ 160 lm/W power LED performance within the next 5 years• Multi-primary white could outperform (need breakthrough green, red)
Outlook: LEDs vs. Conventional Light Sources
Krames et al., IEEE J. Display Technol. 3, 160 (2007)
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1930 1950 1970 1990 2010
Light Source Description ηL(lm/W)500W High-pressure Na 150140W Metal Halide 122‘TL HE’ Tube Fluorescent 105Halogen-IR Incandescent 30Standard Incandescent 16
Best low-current
LED
halogen
metal halidehigh-pressure Na
fluorescent
Pow
er L
EDs
Hg vaporhalogen-
IR
U.S
. DO
E ro
adm
ap
(LED
s)
incandescent
Best high-power LED
Lum
inou
s Eff
icac
y (lm
/W)
4Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
White LED Performance“Cool” CCT ~ 4500 – 10,000K
• Small 5mm LEDs– Lower current density– Lower forward voltage
• Power LEDs– More lumens/package– Lower cost per lumen
Pum
p B
lue
WP
E (e
st.)
Current Density (A/cm2)
Lum
inou
s E
ffica
cy (l
m/W
)
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10%
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70%
Power LED~2004
Power LEDLab results
Small LEDLab results
Small LED 2006
~20 mA ~350 mA
Power LED2006
Power LED2007
Small LED 2007
5Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
The Four Elements of LED TechnologyEpitaxy and
MaterialsDevice (chip)
designPackagePhosphors
Important metrics:External quantum efficiency:
EQE = IQE x EXE
Power conversion efficiency:PCE = EQE x Eph / Vf
Luminous efficacy:LE = PCE x V(λ)
6Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
0%
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350 450 550 650
1) Philips Lumileds TFFC LEDs 2) Morita et al., Jpn. J. Appl. Phys. 43, 5945 (2004)3) Nichia, ICNS-74) Philips Lumileds TIP LEDs
InxGa1-xNInxGa1-xN (AlxGa1-x)0.52In0.48P(AlxGa1-x)0.52In0.48P
(2)
(1)
Tj = 25°CTj = 25°C
Exte
rnal
qua
ntum
eff
icie
ncy,
ηex
tEx
tern
al q
uant
um e
ffic
ienc
y, η
ext
Peak wavelength, λp (nm)Peak wavelength, λp (nm)
(4)
High-power ( 1 Watt input) visible -spectrum LEDs~>~>High-power ( 1 Watt input) visible -spectrum LEDs~>~>
(3)
V(λ)
(3)
• InGaN– Maximum external quantum efficiencies in the blue– Lower efficiency with increasing InN % (~ 2x reduction green)
• AlGaInP– Fundamental bandstructure limitations at short wavelengths
High-Power (> Watt Input) LED Performance
7Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
RGB 540
400 450 500 550 600 650 700
Wavelength (nm)
R
R-G540-B White LED for Illumination
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300
0% 20% 40% 60% 80%
Green LED Efficiency (WPE)
Whi
te S
ourc
e Ef
ficie
ncy
(lm/W
)
0.20.40.75
•If nitride RGB all reach ≥ 75% WPE (very unlikely requiring three “miracles”) then the source efficacy would be ~280 lm/W before color mixing losses (possibly 15-30% which would imply about 200 lm/W → 240 lm/W)
•If RGB all reach >40% WPE (much more reasonable to expect) then ~150 lm/W source would be achieved which would be color tuneable
•Green is the key for enabling color tuneable white illumination to occur
Red - 615nmBlue - 460nmGreen - 540nm
CRI – 90CCT - 3270
Blue WPE - 75%Red WPE - 75%
Red WPE - 40%
Red WPE - 20%
Red, Green, Blue Color Mixing for Warm White Illumination
8Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Recent Development: Improved Epitaxial Materials Process Reduces “Efficiency Droop” at High Current Densities *
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Device input current (mA)
Nor
mal
ized
EQ
E (%
)
PLL high currentefficiency solutionCurrent Production
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100%
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Device current (mA)
Nor
mal
ized
rad
iant
flux
(% m
ax. W
)
PLL high currentefficiency solutionCurrent Production
• High efficiency maintained to over 1.5A
• >20% flux gain at high current densities (> 1.0A)
• Key step forward for achieving a high efficiency 1000lm emitter in a single 1mm2 chip
• Auger effect is key issue. Improvement is to use a thicker active layer. (DH vs QW’s)
*Nate Gardner, et. al., presented at ICNS-7, Las Vegas, NV, September 16-21, 2007
*Yu-Chen Shen, et. al., “Auger recombination in InGaN measured by photoluminescence,” APL, (2007)
9Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Thin ASThick AS
Thick AS + DBRTS
Improved TS
Shaped TS
Thick RS
CC(PS/ITO)low power
CC (PS/ITO)high power
TFFC
CC
FC (Al)
CC (PS)FC (Ag)
VTF
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1990 1995 2000 2005 2010Year
Lig
ht E
xtra
ctio
n E
ffici
ency
, Cex
t (%
)Li
ght e
xtra
ctio
n ef
ficie
ncy,
Cex
t(%)
Year
(f) Thick RS
(a) Thin AS
(e) Shaped TS
(b) Thick AS (c) Thick AS + DBR
(d) Thick TS
(Al,Ga)InPwb pad
host substrate
GaAs GaAs GaAs
(Al,Ga)InP + window layer
DBR
n-GaP substrate
p-GaPn-GaP
substrate
p-GaPmetal
(Al,Ga)InP-GaAs or (Al,Ga)InP-GaP
InGaN-GaN-Al2O3
LED Chip Design
• Dramatic improvement last 15 years• Light extraction efficiencies reach
~80% (InGaN) and 60%+ (AlGaInP)
(a) Conventional Chip - CC (b) Flip Chip - FC
(c) Vertical Thin Film - VTF (d) Thin Film Flip Chip - TFFC
Al2O3
n-type
p-wb pad
p-type
p-spreader
n-wb pad
Al2O3
p-typen-type n contact
n-wb pad
n-typep-type
reflective metal bond
host substrate
n-typep-type
n contact
reflective p contact
reflective p contact
light extraction features
10Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
State-of-Art Power LED Chip Design
• Flip Chip LED (FC)– Excellent heat extraction– No wire bonds– High extraction efficiency
• Thin Film Flip Chip LEDs (TFFC)– Highest extraction efficiency– Lambertian radiation pattern Flip Chip LED
QW(s)p-GaN
n-GaN
Sapphire
Submount
hν
Agp-contact
Thin Film Flip Chip LED
QW(s)p-GaN
n-GaN
Submount
hν
Agp-contact
LambertianTFFC LED
TFFC LED
FC, TFFCLED array with lens
Vertical chipLED array with lens
Lambertian radiation patternof TFFC LED
Heat Heat
Heat Heat
Sapphireremoved
11Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
0.39
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32 5030 50
285 02 67 0
2 54 0
2 00 00
45 00 0
in f
Y e l lo w P h o s p h o r
6 5 0 0 K + /-2 0 0 K3 0 0 0 K + /-5 0 K
Key Challenge: PC-White CCT Variation
• Imperceptible color variationfor human eye:
– 6500 K: ±200 K– 3000 K: ±50 K
• Manufacturing challenge– Blue wavelength range– Control of phosphor
deposition process
Phosphor layer LED
LED chip LED chip
Phosphor coating
Luxeon LEDs:
Conformal phosphorcoating
Phosphorparticles
10…20x reduction inCCT distribution desired
Conventional LED:
“Slurry deposited”phosphor particles
Blue wavelength range
Phosphorlayer
thickness
Yellow Phosphor
Warm-whitecolor bins
Cool-whitecolor bins
Large variation in CCT
12Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
0.0
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0.0 0.1 0.2 0.3 0.4 0.5 0.6
u'v'
Pump WLdistribution
YAG:Ce
PlanckianLocus
Increasingabsorption
CIE Chromaticity
Diagram
460 nm
440 nm
CCT ~5000 K
Improvement: Solid-State Phosphor Element
• Lumiramic phosphor technology™– Sintered YAG:Ce ceramic– Matches TFFC LED chips– Optically homogeneous solid-state material
• White LEDs with Lumiramic phosphor technology™– Precision in phosphor absorption via
plate thickness control– 4x Reduction in number of color bins– High luminance and excellent color stability
QW(s)p-GaN
n-GaN
Submount
Agp-contact
Lumiramic™ YAG:Ce Plate(not to scale)
TFFC LED with Lumiramic™
Lumiramic platelets
13Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
0.01
0.1
1
10
100
1960 1970 1980 1990 2000 2010 2020
YearP
ower
han
dlin
g pe
r LE
D (
W)
State-of-Art LED Packages - Power Handling
• Power handling capability– LUXEON K2 >5 W– Luxeon Rebel ~3 W– Future >10 W
• Lumen maintenance– Strong function of
• Junction temperature (TJ)• Drive Current (If)
– Typical: 50,000 hour
Power handling increased>100 x in last decade
(B50, L70) Lifetime
Power Handling per LED
“5 mm”lamp
“Superflux”LUXEON I
LUXEON K2
LUXEONRebel
Future
LUXEON K2
14Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
State-of-Art LED Packages
• LUXEON K2– Highest flux– Highest drive current (If ≤1.5 A)– Highest operating temperature (TJ ≤185°C)– Lowest cost of light
• LUXEON Rebel– Highest flux-density (footprint: 3 x 4.5 mm2)– High operating temperature (TJ ≤150°C)– High drive current (If ≤1 A)– Highest flux/$ power LED
LUXEON K2
d ~1
5 m
md
~15
mmr = 2.13 mmr = 2.13 mm
Example: Color mixing
• Small size reducesfocal length
– smaller optical systems– smoother mixing in small spaces
• First power LED “pixel solution”
LUXEON Rebel
15Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Ultra Small, Low Cost Power PackagingLUXEON Rebel Platform
Performance:• Size: 3x4.5mm vs. 7.2 x 7.2mm • Light output, efficiency, reliability leader in 350mA – 1A class• Packing density: Up to 6x other power LEDs• Lowest cost/improved Lumens/$• Outperforms Chip-on-Board (performance, reliability)
Winner: Technical Excellence Award
16Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Introducing LUXEON K2 with TFFC– Utilizes the latest TFFC die for dramatically improved light output
• Light output bins start at min 160 lumens in white– Lowest Thermal Resistance: 5.5°C/W– Highest Maximum Junction Temperatures:
• 185°C for direct colors, 150°C for white– Tested and binned exclusively at 1000mA– Available first in cool-white to be followed by
warm-white, neutral-white, blue and green – Lead-free reflow solder JEDEC 020c compatible
17Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
LUXEON Automotive Forward Lighting SourceKey Performance Attributes:
– Automotive Reliability– High Power Density (> 4 W/mm2)– High Temperature Operation– World class lumen output:
• Today: 750 lumens @ 1A per 1x4• Future: >>1500 lm @ 2.3 A
– High luminance• Today: 45 MNits @ 1A per 1x4• Future: >90MNits
2008 Audi R8
Halogen: ~ 20 MNits
LAFLS: ~ 45 MNits
Prototype AFL LED Package
AFL LED elements
Prototype package
18Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Performance: Evolution of LED source brightness
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
1960 1970 1980 1990 2000 2010 2020
Lum
inan
ce (c
d/m2 )
Fluorescent
Halogen HID
unfiltered*
LEDs
Indi
cato
r D
ispl
ays
Aut
o-m
otiv
e
Proj
ectio
nIl
lum
inat
ion
gene
ral
sp
otPr
ojec
tion
Lum
inan
ce (c
d/m
2 )
TFFCLED, 1 A
• Focus on power LEDs has accelerated luminance performance.• LED brightness on target to match that of the UHP bulb.
filtered
UHP
*collected flux of 4500 lm within 15 mm2-sr, an étendue typical for micro-display projection (G. Derra, J. Phys. D: Appl. Phys. Vol. 38, pp. 1995-3110, 2005)
19Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
1000-Lumen Single Emitter (White)
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Luminous Efficiency (lm/W)
Heat
Gen
erat
ion
(W)
Active Cooling
Passive Cooling
1000 lm Single Emitter(White)
1000-Lumen Single Emitter (White)
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1000-Lumen Single Emitter (White)
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erat
ion
(W)
Active Cooling
Passive Cooling
1000 lm Single Emitter(White)
Heat Management: Easier in the Future
• LEDs pass all heat back to heat-sink and fixture• Today’s efficiency: Thermal management remains an issue and adds cost• Future efficiency: Heat management should be straightforward• Circuitry for driving LED is a large cost factor for replacement lamps. As LED
efficiency goes up circuit cost will go down, but will likely remain a key issue
If PCE = 50 %,LE = 150 lm/W
20Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
LUXEON Applications Around the World
Mega Bridge, Bangkok, ThailandPhilips
Bosphorus Bridge, Istanbul, TurkeyPhilips
Technopolis, Athens, GreecePhilips
21Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
High-power LED Applications: RGB White
• Illumination• LCD Backlighting• Projection
• LUXEON I and LUXEON III• Replicates day-light
without harmful ultra-violet or infra-red radiation
• Exact color rendition
SONY Qualia 005
• TriluminosTM LED backlightfor LCD panel
• Ultra-high color gamut(105 % NTSC)
• LEDs eliminate motion artifact• Mercury free• Long life
Pocket Projectors• Flux: 12 – 100 lm• Power: 10 – 25 W• Weight: 1 – 1.5 lb• Battery life: 2.5 hToshiba TDP-FF1A
Mitsubishi PK-10
Samsung SP-P300M
Mona Lisa Lighting by Fraen Corporation
22Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
High-power LED Applications: PC White
• Portable lighting• Mobile phone camera flash• Illumination• Automotive forward lighting
S6
Casino Breda, Netherlands by Bocom
• LUXEON V• 2 – 80 variable lumens• 1 - 40 variable hours• Non imaging optics
• Functional flash (<~3m)• LUXEON Flash• LUXEON Module
Surefire DEF 1
S6S8
Daytime Running Light (DRL)• Multiple LEDs per DRL• 100°C ambient temperature
23Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Why are LEDs Not Yet Widely Used for General Illumination?
• Cost has been too high
• Efficiency has been too low
• White “color” needs to be warmer and better controlled
• Engineering challenges: thermal, optical, electrical
• Other Issues: Standards, complimentary infrastructure, stable supply, etc.
24Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Key Challenge: Cost/lumenThe conventional technologies are much lower in cost
~10.0 (best case-without driver!)White LEDs:
~2.0 (and going lower)CFLs:
~0.6Fluorescents:
~0.4Incandescents:
$/1000 lm
Need > 10xreduction!
How do LEDs get closer?
Total 12x
2xLower chip and packaging costs
3xHigher drive currents (700 mA to 2A)2xEfficiency improvement (75 lm/W to 150 lm/W)
Gain Factor LEDs are more competitive when total cost of ownership and
environmental factors (no mercury) are considered
25Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
1
10
100
1000
1995 2000 2005 2010
Year
Max
. Whi
te L
umen
s
Outlook: Goals for Phosphor White for Illumination
• Single-emitter Flux (“Power” LED)
1000 lm target– same as 60 W light bulb– today’s LEDs: 100-200lm ea.
• Cost of Ownership (COO) Analysis – 1000 lm source
$ 240$ 48$ 48$ <160 W1 X 60 W incandescent
$ 90$ 20$ 18~ $ 220 W1 x 20 W Compact Fluor.
~ $ 6
$ 33
COO(1 yr)
~ 6 W
14 W
InputPower
~ $ 26$ 5~ $ 11 x 160 lm/W LED
$ 85 $ 13$ 2010 x 1-W TFFC emitters
COO (5yrs)
Energy cost/yr
Source cost
Target: ~160 lm/W, 1000-lm LED
5 mm lamp
Early LUXEON I LUXEON III
LUXEON K2
at $0.10 per kWh
26Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
Outlook: How achievable is 160 lm/W, 1000-lm LED?
• High-current-density (~ 250 A/cm2) efficiency is critical• Blue internal quantum efficiency (IQE) must increase by > 2x• Must reduce forward voltage (ongoing programs)• Warm white would be lower by (10 - 30%)
Light Extraction Eff.Internal Quantum Eff.
Forward Voltage
Luminous Efficacy*
~80~36EQE (%)
~2.9~4.2Vf (V)
~75~25PCE (%)
PC White
~160~61LE (lm/W)
~90~40IQE (%)
~90~90Cext (%)
FutureToday
2000 mA : 1x1 mm2For single 1000-lm emitter, 2 A drive current needed
*assumes 250 lm/Wopt phosphor conversion for cool white CCT ~6000
27Philips Lumileds Lighting Company, M. George Craford, IMAPS November 14, 2007
• Power LEDs are improving rapidly. Commercial performance in the 100 lm/W range is beginning, and ~150 lm/W should happen within five years
• Key issues for conversion to LEDs include: More lumens, lower cost, complementary infrastructure, standards, and consistent high volume supply
• Performance improvement for green devices is a key issue for RGBtuneable white
• It is clear that LEDs will dominate general illumination. The only question is timing
• Full conversion at 150 lm/W will reduce electricity used for lighting by ~50% and “save” over 100 nuclear reactors worldwide
Summary
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