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Development of LED lighting: Highlights and Predictions

Steve DenBaars, S olid State Lighting and Energy Electronics

Materials Dept

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1. Energy Savings potential of GaN LEDs, Current status, problems

2. Physics of Gan LEDs

3. Future: Intelligent LEDs and Laser Lighting

Outline


Electricity Consumption in CA by End Use

Lighting accounts for ~34% of electricity consumption in CA! 22% National Average

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2009 Data


DOE Solid State Lighting MYP March 2011

Lighting Efficiency 168 lm/W UCSB, R&D

~50-90 lm/W Mfg. basis


Lighting accounts for ~20% of the total electricity consumption in the USA With implementation of LEDs (2010-2030):

Electricity consumption from lighting in the USA reduced by ~46% Cost savings > $250 billion Reduce greenhouse gas emissions by 1800 million metric tons of carbon

http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/ ssl_energy-savings-report_jan-2012.pdf

Energy Savings Potential with SSL without LEDs

with LEDs


Overall Lighting System Efficiency

4/30/14 6 Courtesy Cree Inc


Solid-state lighting (SSL)

Backlighting

Decorative lighting Automotive lighting

Plant growth Indoor lighting

Applications for GaN LEDs


Future of SSL & Power: GaN on GaN

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1. GaN Lattice matched structure Low defect density (< 1E+5 cm-2), High throuput Epi&Fab 2. Conductive substrate Uniform current flow and high current density, simple mask design 3. Low Efficiency Droop Semipolar 5-10x current flow, Chip area 1/10th 4. High thermal conductivity & Low Thermal Droop Good heat spreading and smaller heat sink (lower cost)

10 Sapphire/Thin GaN LEDs = 1 bulk GaN LED


C-Plane and Nonpolar GaN Semi polar GaN

GaN Crystal Planes


Two Biggest Problems w/ White LEDs

Thermal Droop

UPDATE!! Quantum Efficiency

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0.2

0.4

0.6

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0 10 20 30 40 50 60 70Current Density (A/cm)

Eff

icie

ncy

Efficiency Droop

Peak Efficiency

Current Droop of Chip

Press Release 150lm/W ACTUAL Commercial LEDs 70-80 lm/W (warm white)


GaN on GaN: Improved Efficiency droop LEDs

UCSB c-plane (2009) > -50% at 70 A/cm2 UCSB semipolar (2012) -14% at 300 A/cm2


Reduced Efficiency Droop Semipolar LEDs

UCSB c-plane (2009) > -50% at 70 A/cm2 UCSB semipolar (2012) -14% at 300 A/cm2


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Future trends: Intelligent LEDs

& Laser Lighting


14 2/08/12

Source:www.electronicsbus.com

Li-Fi communication network Sensor, Alarm System, Social Preference Higher capacity than Wifi.

Intelligent LED Light and Communication System


Laser + Phosphor Lighting Beyond display, specialty illumination

segments are now exploring laser lighting High brightness applications are first 5x Advantage for Directed Beam (Casio

Projector on market)

Reduced system costs (streetlights, projection, fiber based)

LD Based White GaN Lasers currently 30% wall-plug

efficiency,

30% WPE83lm/W (present) 75%WPE -> 200lm/W (future)

UCSB 83 lm/W White LD pumped


Laser Based White Lighting

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83 lm/W with WPE of 24% Commercial LD EQE as high as 53% CCT: 4200-6200 K CRI: 56-71

Laser Diodes are Droop Free across a wide current range

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100 Inch GaN Laser TV

GaN Laser Will Impact Displays & Lighting

Visibility Range: Laser High Beam, LED High Beam, Low beam

Increase Nightime Visibility >700m

700m


GaN on GaN Applications

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GaN on GaN

Power Devices Solid State Lighting Laser Diode

EV Car PV Inverters LED Lighting Outdoor Car Headlight Laser TV


Summary

Key breakthroughs accomplished in basic GaN materials and devices has enabled high efficiency lighting.

LED Efficiencies now at 50-90 lm/Watt in market, Next generation of products will be150 lm/W, potential for greater than 250 lm/W

Low-droop and high-efficiency GaN on GaN LEDs have been demonstrated

Blue LEDs with >50% EQE at 100A/cm2 and 450mW LOP at 400A/cm2

Blue(450nm) and green (525nm) nonpolar and semipolar laser diodes achieved


Thank you for your attention!

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