Light-Emitting Diodes (LEDs) for Illumination Applications
Light-Emitting Diodes (LEDs) for Illumination Applications Mike Krames, CTO
LIGHTING IS… …fundamental to life
…consuming 20% of world’s electricity …a ~ 100B USD market
Dec 3, 2012 • Stanford University
2
1 LED Fundamentals
LIGHT-EMITTING DIODE (LED) • • • • •
Monocrystalline atomic arrangement determines bandgap & optical properties Impurity doping provides p- and n-type regions At forward bias, injected electrons and holes recombine Energy may be released radiatively (light) or non-radiatively (heat) Fundamentally non-destructive
Dec 3, 2012 • Stanford University
4
LUMINOSITY • Human eye is not equally sensitive to all wavelengths of light
• Eye sensitivity is represented by the Luminosity Function, V(λ) (CIE) Luminosity Function UV
1 Watt at 555 nm = 683 lumens • Lumens decrease in the blue and red spectral regions
2/8/12
Lumens per Watt
• Definition:
Visible Spectrum
Infrared
V(λ)
5
LEDs: FUNDAMENTALLY BETTER UV
INFRA-RED VISIBLE
• 2900K White, Equal-Lumen Spectra
Incandescents 95% heat
•
Fluorescents
Spectral Irradiance, W m-2 nm-1
Max. efficiency ~ 50%
•
LEDs “ultimate lamp”*
Tri-phosphor Fluorescent Lamp (FL)
Incandescent Tungsten LED ~ 5 eV
Hg
200
LED FL
1000
Wavelength, nm
Stokes’ loss
10000 *N. Holonyak, Jr., et al., Am. J. Phys. 68, 864 (2000)
Dec 3, 2012 • Stanford University
6
III-V MATERIALS SYSTEMS FOR LEDs
Dec 3, 2012 • Stanford University
7
WHITE LIGHT GENERATION WITH LEDs • RYGB White Mixing Optics
Multi-Primary Color Mixing – Color tunability option – Requires color control – Requires color mixing optics
RYGB LEDs
• Down-Conversion Materials – Typically inorganic phosphors – Disadvantage: Stoke’s shift – Advantage: integrated color mixing after Mueller-Mach et al., phys. stat. sol. (a) 202, 1727 (2005)
Dec 3, 2012 • Stanford University
8
EVOLUTION OF LED PERFORMANCE
1000
Luminous Efficacy (lm/W)
white theoretical limit InGaN-based PC White
100
Shaped/Textured AlGaInP AlGaInP/GaP AlGaInP/GaAs
10
HID FL
High-Intensity Discharge
W-H W
Tungsten-Halogen
Fluorescent
Tungsten
AlGaAs/AlGaAs InGaN
1
AlGaAs/GaAs GaAsP:N GaP:Zn,O
InGaN
GaAsP
0.1 1960
1970
1980
1990
2000
Dec 3, 2012 • Stanford University
2010
2020
9
LED APPLICATIONS (12.5B USD in 2011)
Dec 3, 2012 • Stanford University
10
2 LEDs for Lighting Applications
ENERGY SAVINGS POTENTIAL By 2030, LEDs can save (U.S. only):
Forecasted U.S. Lighting Energy Consumption and Savings
300 TeraWatt hours of energy p. a. (50 1-GigaWatt power plants) $30 Billion 200M metric tonnes carbon emission
Worldwide savings ~ 4x higher Source: Energy Savings Potential of Solid-State Lighting in General Illumination Applications. Prepared by Navigant Consulting, Inc., for the U.S. Department of Energy, Washington, D.C., January 2012.
Dec 3, 2012 • Stanford University
12
LED FABRICATION FLOW
SUBSTRATE Sapphire Silicon Carbide (Silicon)
EPITAXY GaN MOCVD (MBE)
WAFER FAB Lithograpy Metallization Etching
DIE FAB Singulation
PACKAGING Die-attach Interconnect Phosphor
LUMINAIRE Driver Optics Heatsink Assy.
MOCVD = metal-organic chemical vapor deposition MBE = molecular beam epitaxy
Dec 3, 2012 • Stanford University
13
CONVENTIONAL InGaN-GaN LED Typically Lz ~ 2-3 nm InGaN multiple quantum wells (MQWs) Spontaneous and Piezoelectric Polarization Fields complicate bandstructure AlGaN “electron blocker” layer for electron confinement Symmetric carrier injection not a given (mhh >> me) p-electrode Current spreading (e.g., ITO)
p-GaN p-AlxGa1-xN n-electrode n-GaN
p-AlGaN
• • • •
nucleation layer
sapphire www.str-soft.com
Dec 3, 2012 • Stanford University
14
INTERNAL QUANTUM EFFICIENCY Internal Quantum Efficiency is the fraction of electrical current converted to photon emission Product of injection efficiency (fraction of injected carriers that recombine in active region) radiative efficiency (fraction of electron-hole pairs that recombine to emit photons)
ηint = ηinj ⋅η rad Jtot e-
J rec ηinj = J tot Jleak Ec P-GaN
p-AlGaN
InGaN
n-GaN
Jrec
Dec 3, 2012 • Stanford University
15
A-B-C RECOMBINATION MODEL η rad
Rrad Bn 2 = = Rtotal An + Bn 2 + Cn 3
2np = An n+ p
A = Shockley-Read-Hall (crystal defects)
GSRH = A
B = Spontaneous emission
GRad = Bn 2
C = Auger scattering
G Auger = Cn 3
Dec 3, 2012 • Stanford University
trap
16
LIGHT EXTRACTION EFFICIENCY • Light extraction efficiency is the fraction of light that escapes semiconductor chip • Exacerbated by high optical refractive indices n(GaN) ~ 2.4, n(AlGaInP) ~ 3.5
• Product of ηint and Cext is external quantum effciency, ηext
ηext = ηint ⋅ Cext
Dec 3, 2012 • Stanford University
17
LIGHT EXTRACTION EFFICIENCY Dramatic improvement last twenty years Light extraction efficiencies reached ~80%+ (InGaN) and 60%+ (AlGaInP) 100 Light Extraction (%) Light extractionEfficiency, efficiency, C Cext ext (%)
• •
90 TFFC
80
CC(PS/ITO) low power
VTF
70 Shaped TS
60
CC (PS) Thick RS
50
CC (PS/ITO) high power
FC (Al)
40
Improved TS
30
CC TS
20 10
FC (Ag)
Thick AS + DBR Thick AS Thin AS
into silicone or epoxy (n ~ 1.5)
0 1990
1995
2000
2005
2010
Year after Krames et al., JOURNAL OF DISPLAY TECHNOLOGY, VOL. 3, NO. 2, JUNE 2007 Dec 3, 2012 • Stanford University
18
LIGHT EXTRACTION TECHNIQUES Vertical Thin Film (VTF)1
Thin Film Flip Chip (TFFC)3 1) 2) 3) 4)
Patterned Substrate (PS)2
Shaped Transparent Substrate (TS)4
B. Hahn et al., Proc SPIE 6910:691004 (2008) Y. Narukawa et al., J. Phys. D: Appl. Phys. 43: 354002 (2010) O. Shchekin et al., Appl Phys Lett 89:2365–2367 (2006) M. Krames et al., Appl Phys Lett 75(16):071109 (1999)
Dec 3, 2012 • Stanford University
19
EXTERNAL QUANTUM EFFICIENCY InGaN 1
2
AlGaInP V(λ)
1) M. Cich et al., Appl. Phys. Lett. 101, 223509 (2012); doi: 10.1063/1.4769228 2) Y. Narukawa et al., J. Phys. D: Appl. Phys. 43 (2010) 354002 3) R. Mueller-Mach et al., Phys. Status Solidi RRL, 1–3 (2009) / DOI 10.1002/pssr.200903188 Other: Janglin Chen, Wayne Cranton, Mark Fihn (eds.), Handbook of Visual Display Technology, DOI 10.1007/978-3-540-79567-4_6.4.1, # Springer-Verlag Berlin Heidelberg 2012
Dec 3, 2012 • Stanford University
20
PHOSPHOR-CONVERTED WHITE LEDs blackbody
3000K
350
450
550
650
750
Wavlength (nm)
Janglin Chen, Wayne Cranton, Mark Fihn (eds.), Handbook of Visual Display Technology, DOI 10.1007/978-3-540-79567-4_6.4.1, # Springer-Verlag Berlin Heidelberg 2012
Dec 3, 2012 • Stanford University
21
LIGHTING MARKET
• 30+Billion world wide installed sockets • 90 Tera-lumen capacity for these sockets • Socket penetration by LED lighting is 1 kA.cm-2 • Low Dislocation Densities required • Quasi-Bulk GaN substrates based on Hydride Vapor Phase Epitaxy (HVPE)
GaN HVPE Substrate
S. Tomiya et al., IEEE Sel. Top. Quantum Elect. 10, 1277 (2004).
Dec 3, 2012 • Stanford University
28
GaN on GaN: NATIVE SUBSTR. ADVANTAGE •
Growth plane option
•
Ultra-low dislocations (to < 104 cm-2)
•
Reliability at high current density
•
High thermal conductivity
•
Breakthrough in lumens density
•
Reduced droop
•
Simplified chip architecture & mfg
Dec 3, 2012 • Stanford University
29
LED FABRICATION FLOW SUBSTRATE Sapphire, Silicon Carbide, (Silicon)
EPITAXY GaN MOCVD, (MBE)
WAFER FAB Lithograpy Metallization Etching
DIE FAB Singulation
PACKAGING Die-attach Interconnect Phosphor
Gallium Nitride (GaN)
AP MOCVD (GaN)
Simple Flow
Proprietary Dicing
Proprietary Unique Design Si-wafer based packaging
Dec 3, 2012 • Stanford University
LUMINAIRE Driver Optics Heatsink Assy.
30
GaN on GaN™: LED FABRICATION • No substrate removal
Light Extraction • Single optical refractive index • Volumetric emitter: Surface/Junction area >> 1
*Simulation
Light Extraction Efficiency
Simple fabrication process
Volumetric chip
Thin-film chip
• Tri-lateral (“Tri-LED”) configuration
Chip Height (µm)
• Approaching 90%*
Photon escape
Dec 3, 2012 • Stanford University
SEM image of a Tri-LED chip
31
GaN on GaN™: LED PERFORMANCE Peak external quantum efficiency of 73%
~ 850 mW at 500 mA
External Quantum Efficiency
Extremely low droop
Pulsed, 300K, λ ~ 410 nm Y. Narukawa et al., J. Phys. D: Appl. Phys. 43 (2010) 354002
Output Power (W)
Commercially available package with silicone encapsulation
InGaN-GaN Heterostructure Tri-LED on Native GaN Substrate
15-25x smaller than conventional power LED chips Forward Current Density (kA cm-2)
Dec 3, 2012 • Stanford University
32
GaN on GaN™: POWER DENSITY Conventional LED • Unprecedented power density uniformity • No current crowding • Quiescent point optimization D. Kuo et al., Materials Science in Semiconductor Processing, Volume 15, Issue 1, February 2012, Pages 52–55
1.4
Intensity (arb. units)
1.2 1 0.8 0.6 0.4 0.2
0.5 kA.cm-2
0
-150 -100
-50
0
50
100
150
x (µm) Dec 3, 2012 • Stanford University
33
GaN on GaN™ LED RELIABILITY Stable violet flux at 160 Acm-2 and Tj = 140°C operation 5000 hours white-emitter reliability under same drive conditions Single-exponential fit made following TM-21 convention for long-term life predictions
95% Lumen Maintenance at 100khrs
Dec 3, 2012 • Stanford University
34
GaN on GaN™ LIGHTCHIP™ Proprietary Si-based wafer level packaging Multi-die array Red, Green, and Blue phosphor mix Ultra-small (bright) form factor
Dec 3, 2012 • Stanford University
35
GaN on GaN™ LED MR16 LAMPS • Technology differentiation leveraged into most difficult lamp, with unique design • High lumen density • High center beam candle power • Single, high quality beam • Uniform, high quality color • 50W halogen MR16 level (2400 cd, 24°)
SORAA
Other
• Three beam angles (10,25,36) • No mechanical fan! • Up to 80% energy savings (Less than one year payback) Dec 3, 2012 • Stanford University
36
FULL vs. TRUNCATED SPECTRUM Violet- vs. Blue-pumped Photon Energy Loss: 10%
3.0 electron volts
2.7 electron volts
Intensity Dec 3, 2012 • Stanford University
37
Blue
Infrared
• Better match to blackbody curve → Natural colors
Violet
• World’s only Full Spectrum MR16 Product
Ultraviolet
COLOR QUALITY
• Reduced blue overshoot → Circadian Rhythm friendly • Violet → Improved Whiteness
Color Rendering Indices (CRI) Dec 3, 2012 • Stanford University
38
LIGHTING DESIGN “Despite a number of product attempts… none (LED MR16) until recently have posed a reasonable challenge to the performance of the halogen lamps they might replace … … The MR16 lamp that has been introduced based on GaN-on-GaN technology represents a significant leap in LED technology for the huge worldwide MR marketplace, with performance that… rivals common halogen MR16.” James R. Benya, PE, FIES, FIALD. A Critical Advance in MR16 LED Lamps
LED HISTORY: 50 YEARS First GaN GaN on sapphire (polycrystalline) (monocrystalline) P. Maruska I. Akasaki
1962 First LED (red) N. Holonyak, Jr.
1969
1986
Watt-class White LEDs
1993
1999
First Blue LEDs / LDs S. Nakamura
Dec 3, 2012 • Stanford University
Soraa Founded
2006 Bulk-GaN based LEDs / LDs UCSB
2008
2012 First GaN-on-GaN™ Lighting Product
40
LIGHTING IS… …fundamental to life
…consuming 20% of world’s electricity …a ~ 100B USD market
Dec 3, 2012 • Stanford University
2
1 LED Fundamentals
LIGHT-EMITTING DIODE (LED) • • • • •
Monocrystalline atomic arrangement determines bandgap & optical properties Impurity doping provides p- and n-type regions At forward bias, injected electrons and holes recombine Energy may be released radiatively (light) or non-radiatively (heat) Fundamentally non-destructive
Dec 3, 2012 • Stanford University
4
LUMINOSITY • Human eye is not equally sensitive to all wavelengths of light
• Eye sensitivity is represented by the Luminosity Function, V(λ) (CIE) Luminosity Function UV
1 Watt at 555 nm = 683 lumens • Lumens decrease in the blue and red spectral regions
2/8/12
Lumens per Watt
• Definition:
Visible Spectrum
Infrared
V(λ)
5
LEDs: FUNDAMENTALLY BETTER UV
INFRA-RED VISIBLE
• 2900K White, Equal-Lumen Spectra
Incandescents 95% heat
•
Fluorescents
Spectral Irradiance, W m-2 nm-1
Max. efficiency ~ 50%
•
LEDs “ultimate lamp”*
Tri-phosphor Fluorescent Lamp (FL)
Incandescent Tungsten LED ~ 5 eV
Hg
200
LED FL
1000
Wavelength, nm
Stokes’ loss
10000 *N. Holonyak, Jr., et al., Am. J. Phys. 68, 864 (2000)
Dec 3, 2012 • Stanford University
6
III-V MATERIALS SYSTEMS FOR LEDs
Dec 3, 2012 • Stanford University
7
WHITE LIGHT GENERATION WITH LEDs • RYGB White Mixing Optics
Multi-Primary Color Mixing – Color tunability option – Requires color control – Requires color mixing optics
RYGB LEDs
• Down-Conversion Materials – Typically inorganic phosphors – Disadvantage: Stoke’s shift – Advantage: integrated color mixing after Mueller-Mach et al., phys. stat. sol. (a) 202, 1727 (2005)
Dec 3, 2012 • Stanford University
8
EVOLUTION OF LED PERFORMANCE
1000
Luminous Efficacy (lm/W)
white theoretical limit InGaN-based PC White
100
Shaped/Textured AlGaInP AlGaInP/GaP AlGaInP/GaAs
10
HID FL
High-Intensity Discharge
W-H W
Tungsten-Halogen
Fluorescent
Tungsten
AlGaAs/AlGaAs InGaN
1
AlGaAs/GaAs GaAsP:N GaP:Zn,O
InGaN
GaAsP
0.1 1960
1970
1980
1990
2000
Dec 3, 2012 • Stanford University
2010
2020
9
LED APPLICATIONS (12.5B USD in 2011)
Dec 3, 2012 • Stanford University
10
2 LEDs for Lighting Applications
ENERGY SAVINGS POTENTIAL By 2030, LEDs can save (U.S. only):
Forecasted U.S. Lighting Energy Consumption and Savings
300 TeraWatt hours of energy p. a. (50 1-GigaWatt power plants) $30 Billion 200M metric tonnes carbon emission
Worldwide savings ~ 4x higher Source: Energy Savings Potential of Solid-State Lighting in General Illumination Applications. Prepared by Navigant Consulting, Inc., for the U.S. Department of Energy, Washington, D.C., January 2012.
Dec 3, 2012 • Stanford University
12
LED FABRICATION FLOW
SUBSTRATE Sapphire Silicon Carbide (Silicon)
EPITAXY GaN MOCVD (MBE)
WAFER FAB Lithograpy Metallization Etching
DIE FAB Singulation
PACKAGING Die-attach Interconnect Phosphor
LUMINAIRE Driver Optics Heatsink Assy.
MOCVD = metal-organic chemical vapor deposition MBE = molecular beam epitaxy
Dec 3, 2012 • Stanford University
13
CONVENTIONAL InGaN-GaN LED Typically Lz ~ 2-3 nm InGaN multiple quantum wells (MQWs) Spontaneous and Piezoelectric Polarization Fields complicate bandstructure AlGaN “electron blocker” layer for electron confinement Symmetric carrier injection not a given (mhh >> me) p-electrode Current spreading (e.g., ITO)
p-GaN p-AlxGa1-xN n-electrode n-GaN
p-AlGaN
• • • •
nucleation layer
sapphire www.str-soft.com
Dec 3, 2012 • Stanford University
14
INTERNAL QUANTUM EFFICIENCY Internal Quantum Efficiency is the fraction of electrical current converted to photon emission Product of injection efficiency (fraction of injected carriers that recombine in active region) radiative efficiency (fraction of electron-hole pairs that recombine to emit photons)
ηint = ηinj ⋅η rad Jtot e-
J rec ηinj = J tot Jleak Ec P-GaN
p-AlGaN
InGaN
n-GaN
Jrec
Dec 3, 2012 • Stanford University
15
A-B-C RECOMBINATION MODEL η rad
Rrad Bn 2 = = Rtotal An + Bn 2 + Cn 3
2np = An n+ p
A = Shockley-Read-Hall (crystal defects)
GSRH = A
B = Spontaneous emission
GRad = Bn 2
C = Auger scattering
G Auger = Cn 3
Dec 3, 2012 • Stanford University
trap
16
LIGHT EXTRACTION EFFICIENCY • Light extraction efficiency is the fraction of light that escapes semiconductor chip • Exacerbated by high optical refractive indices n(GaN) ~ 2.4, n(AlGaInP) ~ 3.5
• Product of ηint and Cext is external quantum effciency, ηext
ηext = ηint ⋅ Cext
Dec 3, 2012 • Stanford University
17
LIGHT EXTRACTION EFFICIENCY Dramatic improvement last twenty years Light extraction efficiencies reached ~80%+ (InGaN) and 60%+ (AlGaInP) 100 Light Extraction (%) Light extractionEfficiency, efficiency, C Cext ext (%)
• •
90 TFFC
80
CC(PS/ITO) low power
VTF
70 Shaped TS
60
CC (PS) Thick RS
50
CC (PS/ITO) high power
FC (Al)
40
Improved TS
30
CC TS
20 10
FC (Ag)
Thick AS + DBR Thick AS Thin AS
into silicone or epoxy (n ~ 1.5)
0 1990
1995
2000
2005
2010
Year after Krames et al., JOURNAL OF DISPLAY TECHNOLOGY, VOL. 3, NO. 2, JUNE 2007 Dec 3, 2012 • Stanford University
18
LIGHT EXTRACTION TECHNIQUES Vertical Thin Film (VTF)1
Thin Film Flip Chip (TFFC)3 1) 2) 3) 4)
Patterned Substrate (PS)2
Shaped Transparent Substrate (TS)4
B. Hahn et al., Proc SPIE 6910:691004 (2008) Y. Narukawa et al., J. Phys. D: Appl. Phys. 43: 354002 (2010) O. Shchekin et al., Appl Phys Lett 89:2365–2367 (2006) M. Krames et al., Appl Phys Lett 75(16):071109 (1999)
Dec 3, 2012 • Stanford University
19
EXTERNAL QUANTUM EFFICIENCY InGaN 1
2
AlGaInP V(λ)
1) M. Cich et al., Appl. Phys. Lett. 101, 223509 (2012); doi: 10.1063/1.4769228 2) Y. Narukawa et al., J. Phys. D: Appl. Phys. 43 (2010) 354002 3) R. Mueller-Mach et al., Phys. Status Solidi RRL, 1–3 (2009) / DOI 10.1002/pssr.200903188 Other: Janglin Chen, Wayne Cranton, Mark Fihn (eds.), Handbook of Visual Display Technology, DOI 10.1007/978-3-540-79567-4_6.4.1, # Springer-Verlag Berlin Heidelberg 2012
Dec 3, 2012 • Stanford University
20
PHOSPHOR-CONVERTED WHITE LEDs blackbody
3000K
350
450
550
650
750
Wavlength (nm)
Janglin Chen, Wayne Cranton, Mark Fihn (eds.), Handbook of Visual Display Technology, DOI 10.1007/978-3-540-79567-4_6.4.1, # Springer-Verlag Berlin Heidelberg 2012
Dec 3, 2012 • Stanford University
21
LIGHTING MARKET
• 30+Billion world wide installed sockets • 90 Tera-lumen capacity for these sockets • Socket penetration by LED lighting is 1 kA.cm-2 • Low Dislocation Densities required • Quasi-Bulk GaN substrates based on Hydride Vapor Phase Epitaxy (HVPE)
GaN HVPE Substrate
S. Tomiya et al., IEEE Sel. Top. Quantum Elect. 10, 1277 (2004).
Dec 3, 2012 • Stanford University
28
GaN on GaN: NATIVE SUBSTR. ADVANTAGE •
Growth plane option
•
Ultra-low dislocations (to < 104 cm-2)
•
Reliability at high current density
•
High thermal conductivity
•
Breakthrough in lumens density
•
Reduced droop
•
Simplified chip architecture & mfg
Dec 3, 2012 • Stanford University
29
LED FABRICATION FLOW SUBSTRATE Sapphire, Silicon Carbide, (Silicon)
EPITAXY GaN MOCVD, (MBE)
WAFER FAB Lithograpy Metallization Etching
DIE FAB Singulation
PACKAGING Die-attach Interconnect Phosphor
Gallium Nitride (GaN)
AP MOCVD (GaN)
Simple Flow
Proprietary Dicing
Proprietary Unique Design Si-wafer based packaging
Dec 3, 2012 • Stanford University
LUMINAIRE Driver Optics Heatsink Assy.
30
GaN on GaN™: LED FABRICATION • No substrate removal
Light Extraction • Single optical refractive index • Volumetric emitter: Surface/Junction area >> 1
*Simulation
Light Extraction Efficiency
Simple fabrication process
Volumetric chip
Thin-film chip
• Tri-lateral (“Tri-LED”) configuration
Chip Height (µm)
• Approaching 90%*
Photon escape
Dec 3, 2012 • Stanford University
SEM image of a Tri-LED chip
31
GaN on GaN™: LED PERFORMANCE Peak external quantum efficiency of 73%
~ 850 mW at 500 mA
External Quantum Efficiency
Extremely low droop
Pulsed, 300K, λ ~ 410 nm Y. Narukawa et al., J. Phys. D: Appl. Phys. 43 (2010) 354002
Output Power (W)
Commercially available package with silicone encapsulation
InGaN-GaN Heterostructure Tri-LED on Native GaN Substrate
15-25x smaller than conventional power LED chips Forward Current Density (kA cm-2)
Dec 3, 2012 • Stanford University
32
GaN on GaN™: POWER DENSITY Conventional LED • Unprecedented power density uniformity • No current crowding • Quiescent point optimization D. Kuo et al., Materials Science in Semiconductor Processing, Volume 15, Issue 1, February 2012, Pages 52–55
1.4
Intensity (arb. units)
1.2 1 0.8 0.6 0.4 0.2
0.5 kA.cm-2
0
-150 -100
-50
0
50
100
150
x (µm) Dec 3, 2012 • Stanford University
33
GaN on GaN™ LED RELIABILITY Stable violet flux at 160 Acm-2 and Tj = 140°C operation 5000 hours white-emitter reliability under same drive conditions Single-exponential fit made following TM-21 convention for long-term life predictions
95% Lumen Maintenance at 100khrs
Dec 3, 2012 • Stanford University
34
GaN on GaN™ LIGHTCHIP™ Proprietary Si-based wafer level packaging Multi-die array Red, Green, and Blue phosphor mix Ultra-small (bright) form factor
Dec 3, 2012 • Stanford University
35
GaN on GaN™ LED MR16 LAMPS • Technology differentiation leveraged into most difficult lamp, with unique design • High lumen density • High center beam candle power • Single, high quality beam • Uniform, high quality color • 50W halogen MR16 level (2400 cd, 24°)
SORAA
Other
• Three beam angles (10,25,36) • No mechanical fan! • Up to 80% energy savings (Less than one year payback) Dec 3, 2012 • Stanford University
36
FULL vs. TRUNCATED SPECTRUM Violet- vs. Blue-pumped Photon Energy Loss: 10%
3.0 electron volts
2.7 electron volts
Intensity Dec 3, 2012 • Stanford University
37
Blue
Infrared
• Better match to blackbody curve → Natural colors
Violet
• World’s only Full Spectrum MR16 Product
Ultraviolet
COLOR QUALITY
• Reduced blue overshoot → Circadian Rhythm friendly • Violet → Improved Whiteness
Color Rendering Indices (CRI) Dec 3, 2012 • Stanford University
38
LIGHTING DESIGN “Despite a number of product attempts… none (LED MR16) until recently have posed a reasonable challenge to the performance of the halogen lamps they might replace … … The MR16 lamp that has been introduced based on GaN-on-GaN technology represents a significant leap in LED technology for the huge worldwide MR marketplace, with performance that… rivals common halogen MR16.” James R. Benya, PE, FIES, FIALD. A Critical Advance in MR16 LED Lamps
LED HISTORY: 50 YEARS First GaN GaN on sapphire (polycrystalline) (monocrystalline) P. Maruska I. Akasaki
1962 First LED (red) N. Holonyak, Jr.
1969
1986
Watt-class White LEDs
1993
1999
First Blue LEDs / LDs S. Nakamura
Dec 3, 2012 • Stanford University
Soraa Founded
2006 Bulk-GaN based LEDs / LDs UCSB
2008
2012 First GaN-on-GaN™ Lighting Product
40
