Energy Efficient LEDs For Sustainable Solid

Steve DenBaars Solid State Lighting and Display Center

Materials and ECE Departments University of California, Santa Barbara

Engineering Insights Conference UCSB 2008

Energy Efficient LEDs For Sustainable Solid­State Lighting

Steve DenBaars Solid State Lighting and Display Center

Materials and ECE Departments University of California, Santa Barbara

Engineering Insights Conference UCSB 2008

Solid­State Lighting and Display Center

• One of the largest University Cleanrooms (13,000 ft2)

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• World Class MOCVD/MBE Facilities – 6 MOCVD Systems, 7 MBE (3 Nitride)

• Optical Test Facilities (LED and Laser)

• Materials Characterization (TEM,SEM,FIB, XPS, AFM, SIMS)

• Package and Lamp (LED and Laser) Assembly and Test

State Lighting and Display Center

One of the largest University Cleanrooms (13,000 ft2)

7 equipment bays

World Class MOCVD/MBE Facilities 6 MOCVD Systems, 7 MBE (3 Nitride)

Optical Test Facilities (LED and Laser)

Materials Characterization (TEM,SEM,FIB, XPS, AFM, SIMS)

Package and Lamp (LED and Laser) Assembly and Test

UC Santa Barbara Solid State Lighting & Display Center Industry Partners

Matsushita Electric Industrial Co., Ltd.

10 Industrial Partners

UC Santa Barbara Solid State Lighting & Display Center Industry Partners

10 Industrial Partners

Solid State Lighting UCSB Contributors (63) Faculty (9) • Prof. Shuji Nakamura • Prof. James Speck • Prof. Umesh Mishra • Prof. Claude Weisbuch • Prof. Evelyn Hu • Prof. Anthony Cheetham • Prof. Chris Van de Walle • Prof. Fred Lange • Prof. Pierre Petroff

Visiting Researchers(8) H. Sato, M. Saito, H. Asamizu, A. Murai, H. Yamada, K. Iso, W. Cheol, F. Diana, H. Hirasawa

Staff & Students(46) Dr. Keller, Dr. Feezel, Dr. Cohen, Dr. Chen, Dr. Choi, Dr. Baker, Dr. Hashimoto, Dr. Appelhans,

Dr. Wu M. Iza, M. Coulter, B. Carrelejo M. Schmidt, A. Tyagi, H. Zhong, C. Moe, N. Fellows, H. Masui, S. Cruz, S. Newman, K.

Vampola, E. Matioli, D. Kamber, E. Letts, A. Getty, R. Farrell, D. Brown, D. Thompson, B. Imer, T. Ben­Yaacov, A. Corrion, M. Tsai, M. Furukawa, N. Fichtenbaum, S. Pimputkar, R. Chung, Z. Jia, A. Hirai, S. Brinkley, A. Tamboli, K. McGroddy, H. Zhong, C. Neufeld

Y. Warner, J. Vasquez, G. Callaway

Solid State Lighting UCSB Contributors (63)

H. Sato, M. Saito, H. Asamizu, A. Murai, H. Yamada, K. Iso, W. Cheol, F. Diana, H. Hirasawa

Dr. Keller, Dr. Feezel, Dr. Cohen, Dr. Chen, Dr. Choi, Dr. Baker, Dr. Hashimoto, Dr. Appelhans,

M. Schmidt, A. Tyagi, H. Zhong, C. Moe, N. Fellows, H. Masui, S. Cruz, S. Newman, K. Vampola, E. Matioli, D. Kamber, E. Letts, A. Getty, R. Farrell, D. Brown, D. Thompson, B.

Yaacov, A. Corrion, M. Tsai, M. Furukawa, N. Fichtenbaum, S. Pimputkar, R. Chung, Z. Jia, A. Hirai, S. Brinkley, A. Tamboli, K. McGroddy, H. Zhong, C. Neufeld

Luminous Efficacy of Various Light Sources

2006

x

Graph taken from www.lampteck.co.uk

LED

Luminous Efficacy of Various Light Sources

Current number for GaN white LED at UCSB is 160lm/W ucsb chip

First white LEDs were only 5lm/W at 20mA (1995)

LED

Lighting System Efficacy

Courtesy Cree Inc

Lighting System Efficacy

Courtesy Cree Inc

What is an LED?

Blue LED

L.E.D.= Light Emitting Diode (Runs on 3.2V DC Power)

What is an LED?

LED produces light by combining Positive and negative charges inside Gallium nitride crystal

L.E.D.= Light Emitting Diode (Runs on 3.2V DC Power)

GaN Emits All Colors of Light (Blue,Green,UV

GaN Emits All Colors of Light (Blue,Green,UV­>White)

Ban the Light Bulb? • “Ban the Incandescent Light Bulb” gaining momentum • California Legislator Lloyd Levine introduces bill to ban the incandescent

light bulb – February 1, 2007 • Australia passes legislation to ban the

light bulb by 2010 – February 21, 2007 • EU to ban light bulbs – March 9, 2007 • United States ????

Ban the Light Bulb? “Ban the Incandescent Light Bulb” gaining momentum California Legislator Lloyd Levine introduces bill to ban the incandescent

Australia passes legislation to ban the February 21, 2007

March 9, 2007

CFL

LED

Lighting: Large Electricity Consumption

Lighting is single biggest users of Electricity

•

•

•

Lighting: Large Electricity Consumption

Lighting is single biggest users of Electricity

Incandescent Light Bulb ­1­4% efficient

Fluorescent – 15­25% efficient

LED­ 25­60% efficient (90% theoretical)

The Advantage of LED Lighting Long life – lifetimes can exceed 100,000 hours as compared to 1,000 hrs for tungsten bulbs.

Robustness – no moving parts, no glass, no filaments.

Size – typical package is only 5 mm in diameter.

Energy efficiency – up to 90% less energy used translates into smaller power supply.

Non­toxicity – no mercury.

Versatility – available in a variety of colors; can be pulsed.

Cool – less heat radiation than HID or incandescent

The Advantage of LED Lighting lifetimes can exceed 100,000 hours as compared to 1,000 hrs

no moving parts, no glass, no filaments.

typical package is only 5 mm in diameter.

up to 90% less energy used

available in a variety of colors; can be pulsed.

less heat radiation than HID or incandescent

White Light White Light

Substrate

UV GaN LED

Blue GaN LED

Green GaN LED

Red GaAs LED

White Light White Light

Multi­Chip, RGB ­best efficiency ­highest cost

UV + Phosphors ­best CRI,color ­uniformity ­low cost ­improved reliability

3 Methods of Generating White LEDs

UV GaN LED

UV light

RGB Light

White Light White Light

Substrate

Blue GaN LED

Blue Light

Green, Red phosphors

UV + Phosphors best CRI,color

improved reliability

Blue + Phosphors ­lowest cost ­30lm/W ­>90%market share

3 Methods of Generating White LEDs

“The Promise” Energy Usage Comparison

0

10

20

30

40

50

60

Light Source

“Best” White LED and Compact Fluorescent vs. 60Watt Light Bulb Comparison

Pow

er Used (W

atts)

LEDs Save 53Watts

“The Promise” Energy Usage Comparison

Light Source

60W Bulb

Compact Fluor. LED

“Best” White LED and Compact Fluorescent vs. 60Watt Light Bulb Comparison

Global Warming/Energy Savings Potential of LEDs

If a 150 lm/Watt Solid State White LED source were developed, then in the United States alone:

• We would realize $115 Billion cum. Savings in 2025* • Alleviate the need of 133 new power stations!* • Eliminate 258 million metric tons of Carbon* • Save 273TWh/year in energy**

* “The Promise of Solid State Lighting” OIDA Report , 2001, http://www.netl.doe.gov/ssl/PDFs/oida_led **A. D. Little, “Energy Savings Potential of SSL” Report for Dept. of Energy, http://www.eere.energy.gov/buildings/info/documents/pdfs/ssl_final_report3.pdf

Global Warming/Energy Savings Potential of LEDs

If a 150 lm/Watt Solid State White LED source were developed,

We would realize $115 Billion cum. Savings in 2025* Alleviate the need of 133 new power stations!* Eliminate 258 million metric tons of Carbon* Save 273TWh/year in energy**

* “The Promise of Solid State Lighting” OIDA Report , 2001, http://www.netl.doe.gov/ssl/PDFs/oida_led­oled_rpt.pdf **A. D. Little, “Energy Savings Potential of SSL” Report for Dept. of Energy, http://www.eere.energy.gov/buildings/info/documents/pdfs/ssl_final_report3.pdf

Light Extraction Eff.

Conversion Efficiency

Key Materials Technologies for Energy Efficient White LED

ZnO mega­cone

Photonic crystal

New phosphors

SLEO low defect

Internal Q. Efficiency

Electrical Efficiency

Key Materials Technologies for Energy Efficient White LED

Semi,nonpolar

New phosphors Contacts, semi­polar

New ZnO

Summary of Nonpolar/Semipolar LEDs • Nonpolar/semipolar LEDs is close to c

0%

10%

20%

30%

40%

50%

60%

350 450 Peak Wavelength (nm)

External Quantum

Efficiency

In x Ga 1­x N

UV

C­plane

Semi­polar

Non­Polar UCSB

UCSB 2006

Summary of Nonpolar/Semipolar LEDs Nonpolar/semipolar LEDs is close to c­plane EQE

550 650 Peak Wavelength (nm)

(Al x Ga 1­x ) .52 In .48 P Polar UCSB

IWN 2006 by Nichia

UCSB 2006

GaN Crystal Structure GaN Crystal Structure

Motivation – Polarization Effects

Spontaneous and piezoelectric polarization cause: 1. band bending 2. charge separation in QW

• Emission red shift • Low recombination efficiency • High threshold current

Growth on non­polar GaN will solve these problems

Polarization Effects

Historical Evolution of Nonpolar/Semipolar LEDs at UCSB

0

10

20

30

40

50

2001 2002 2003 2004 Year

EQE (%

) • Improved output power and EQE in

Historical Evolution of Nonpolar/Semipolar LEDs at UCSB

2005 2006 2007 2008 Year

41% EQE

Improved output power and EQE in m­LEDs.

Current LED Applications

Streetlights

Cell Phone (Nokia)

Traffic signals (Gelcore)

TVs (LED DLP tm

(samsung)

Current LED Applications

tm )

Large Displays (NASDAQ)

Automotive

Laser TV

Mitsubishi "Laser TV" with Arasor and Novalux components (left) and Plasma (right)

Laser TV

Mitsubishi "Laser TV" with Arasor and Novalux components (left) and Plasma (right)

Future SSL Displays Pocket Projector/Cell Phone

Prototype from Novalux using frequency double lasers

Future SSL Displays Pocket Projector/Cell Phone

Prototype from Novalux using frequency double lasers

Solar(Photovoltaics) + LED (Off

“In the few months we have had the White LED lamps the improvement in the children’s academic performance has been absolutely remarkable” Headmaster, Mubarak Village, Pakistan June 2004

www.lutw.org

•Kerosene lighting and firewood are used by 1/3 of the world; they cause countless fires and are very inefficient

•The average villager spends 10 annual income on kerosene.

•LED Lighting costs much less on an annual basis and payback period is just 6 months.

•LED Lighting /Solar Cell Off

www.lutw.org

Light Up The World Foundation

Solar(Photovoltaics) + LED (Off­grid)

“In the few months we have had the White LED lamps the improvement in the children’s academic performance has

Headmaster, Mubarak Village, Pakistan June 2004

Kerosene lighting and firewood are used by 1/3 of the world; they cause countless fires and are very inefficient (0.03 lm/watt).

The average villager spends 10­25% of their annual income on kerosene.

LED Lighting costs much less on an annual basis and payback period is just 6 months.

LED Lighting /Solar Cell Off­Grid

Light Up The World Foundation

Air/Water Purification

• Fruit and Vegetable Storage Life Extended 1 week • Water Purication: UV LED to kill bacteria

Mitsubishi Refrigerator MR­W55H, UV LED 375 nm, 590 nm

Air/Water Purification

Fruit and Vegetable Storage Life Extended 1 week Water Purication: UV LED to kill bacteria

(Credit: Hydro­Photon Inc.)

CONCLUSION • R&D Level LED Single lamp efficacy (150lm/W) now exceeds CFL, but:

• Commercial based LED Lamp Fixtures are much lower 71 LPW due to several factors that need further research and development in – Fixture Efficiency – Heat Sinking – Scale up to Mass production

• Stay Tuned….

CONCLUSION R&D Level LED Single lamp efficacy (150lm/W) now

Commercial based LED Lamp Fixtures are much lower 71 LPW due to several factors that need further research