M A R K E T A N A L Y S I S Optoelectronics

32

Dr Alan Mills PO Box 4098, Mountain View,

CA 94040, USA TeU Fax: +1-65o-968-2383/8416

E-maih amills@inreach.com

Alan Mills reports from Intertech's LED-2ooo

conference in San Mateo, California, USA,

November 13-15. The event was devoted to the production of light emitting diodes and the development of commercial products

based on not just coloured LEDs but also the

recently introduced white LED technology (much in evidence in the exhibition) which could save "the equivalent of 38 nuclear power plants" in 25 years' time.

High-Brightness LEDs lighting up the future

12

10

8

6

4

2

0 1998 1999 2000 2001 2002 2003 2004

Year

Figure 1. Growth in the market for optoelectronic

semiconductors 1998-2004 (source, Gartner Group).

"Soles of

optoelectronic

semiconductor

devices should

grow from about

USS7bn in 1999 to over US$12bn

in 2004." St~. n 8ruderl~:,,

According to Stan Bruderle of Dataquest (in

"LEDs -The Future Couldn't Look Brighter"),

sales of optoelectronic semiconductor devices

should grow from about US$Tbn in 1999 to over

US$12bn in 2004 (Figure 1), a compound annual

growth rate of about 14% (similar to the growth

forecast for silicon-based microelectronics).

Annual growth in LED sales can be split into two

segments:

• older, more mature LEDs (5-7%); and

• new LEDs such as tile nitride-based blue and

whi te LEDs and the red, orange and green alu-

minium indium gallium phosph ide (AIInGaP)

based high-brightness LEDs (15-40%).

Several factors are driving the growth of today's

LED products: the more important ones are

brightness, available colours, power efficiency,

architectural form flexibility, rugged construction

and low applied voltages.These are contributing

to growth in markets such as traffic lights, auto-

motive brake signals and instrument displays,

video displays, airport runway and taxi lights, haz-

ardous lighting, exit and decorative signs, and the

many uses of the n e w white-LED-based products.

Future possibilities include, for example, simpli-

fied, single-fixture traffic signals where the three

colours light up separately and different-shaped

arrangements of the LEDs are used for each

colour to allow recognition by those w h o are

colour blind.There even appears to be an LED

version of the silicon industry's "Moore's Law"

(for IC functionality or performance) in which

LED brightness doubles about every 18 months.

LED lamp/display market leaders arc shown in

Table 1 (based on est imated 1999 revenues), but

this is expec ted to change due to rapid growth

of new companies such as Mingstar, Kingbright,

Ledtech, Everlight and Litc-On. High-brightness

LEDs are potentially a disruptive influence on

the existing lighting industr}, because of the sud-

dcn arrival of upstart products that are superior

in new areas of the per formance envelope and

because of recent pressure for lower p o w e r con-

sumpt ion to reduce peak demand loads.

However, to protect their share of future markets

some major international lighting companies have

been torming joint ventures with LED producers,

e.g. be tween General Electric and EMCORE to

form GELcorc; Philips and Agilent (formerly HP) to

form LumiLeds: and Osram-Sylvania and Infineon

Teclmologies to form Osram Optoelectronics.

1999 sales (USSm

Agi lent 284

Stanley 220

Infineon 216

Mitsubishi 158

Rohm 153

Table 1. The market leaders in sales of LED lamps and displays (source, Gartner Group).

nl-Vs REVIEW VOL 14 - NO I - JAN/FEB 2ooi

Optoelectronics M A R K E T A N A L Y S I S

Two auto related companies have" also diversified

into this arcna: UniroyalTeclmology Corp has

bought the siliccm carbide inauufacturer Sterling

Semiconductor and has a cooperative agreement

be tween Uniroyal Opmelectronics ;rod EMCORE

(as well as spawning start-up Nowalux), while

Toyota has for sometime held a 41% interest in

nitride-based LED manufacturerToyoda Gosei.

Because of their eff icient T and potential energy

savings on a national scale, the n e w genei-ation of

LEDs has not gone unnot iced by LJS govcrnment

agencies (including the US Energy 1.)epartlnent

and the Environmental Pollution Agency) and

imwer generation companies.Additionall.~; their

kmR-lit~:, low power, low voltage and cool opera-

lion have made white LEDs popu "lar for space

'applicalions while the Ir~w power consumpt ion

of coloured LEDs has made the installation of

traffic lights a priorit7 to save on peak power

demands for the electric utility companics.

According to Gary Fernstrom fl'om Paciilc (;as &

Electric (California's biggest utility company),

some of these replacements arc suppor ted by

incentives from the Depar tment of Energy and

the p o w e r companies, with USS36m available in

Califf)rnia for LED traffic signal installation. In the

Northern California PG&E regi(m alone, hc esti-

mates that 5 MV¢' wt)ultl be saved if 50% of the

signals were changed to LED units; worldwide,

hundreds of megawatts could be saved.

Fernstrom notes that energy saving has beconle

very important in many states of the USA,

including Calilornia where since deregulat ion

in 1996 - electricity demand has grown by 30%

but supply by only 6%, leaving an energy sbort-

~hll (including e~vu winter p o w e r shortage

alerts).This is anticipated to be aLmost tO00 MW

in 2(li11, in part caused by recent h idden stand-by

uses fbr always-on items such as computers and

household appliances, plus a recent display-

mania fl~r lighted sol~ drink machines.This short-

age is alsc~ causing some n e w rttlcs to be pro-

pused, such as limiting all exit signs sold in

Califf~rnia to a rating of 5 W or less, eventually

saving 10 MW - more if LED8 are used (as well .as

reducing maintenance cosls and improving safe-

ty~ since they do not m general suffer catastroph-

ic fhilures tike a b lown light bulb). Such a prece-

dent would represent very significant savings if

fullowed by the rest of the world.

According m Rachel Schmeltz from the US

Envirunmental Pollution Agency, one aspect

of their Energy Star efficiency programme to

~ 40 O

K

~ 20

O

IU

° ~

• . , " ,-GAP

100 mA (dc), Ta=300 K

°5~- 610 630 650

Peak wavelength (rim)

promote LED signs has been rated a resounding

success.The paybacks are less than one year and

provide a reduction in carbon emissions.A 75%

energy reduction in lleW exit signs results in ann-

ual savings <.ff 2bn kW-hr.The IIS Government has

required Energy Star labelled products to be used

since 1999, but ma W states in the USA still have

to lormally adopt the programmc (which also

includes specifications for olher traffic signals).

Reviewing the lineage of the high-brightness LED,

George Cmford of LumiLeds reckons that the

cost per h ,mcn of the lowly red LED (which

began life in 1960) has improved lO-fnld for

eve D" decade fi-om less than 0.1 lumen/Watt to

the host red and orange LEDs now providing

about loll l / ~ T h e retl LED has been a real suc-

cess sto D, where - per decade - the light output

has increased 30 fold per decade.

Significantly, the light gcneralion ell]ciency of

these single/source LEt) chips has improved to

where today's quantum efficiencies arc very high

so that the main engineering challenge is now

the extraction efficiency, or the ability tt~ gel all

the light {rot of the chip to where it is needed.

This has led to novel changes in the shape of the

LED chip and to the replacement of the gallium

arsenide pmduc t inn wafer with transparent galli-

um p lmsphide (through wafiq" bonding after the

LE1) has been produced, as in the case of the

high-brighmess orange LEDs). By using a "truncat-

ed-inverted-pyramid" design (see Figure 2), the

external quantum efficiencies n o w exceed 50%

fi~r the orange LEDs so that more than 12t)

lumens can bc extracted from one chip on a

pulsed output basis.

According to HenryArcand of Ecolux Ine (now a

subsidiary of GELcore) the market R~r t,EI) traffic

lights has progressed fi'om the first installation ol

Figure 2. AIInGaP/GaP truncated-inverted-pyramid (TIP) LEDs.

"Since deregulation in

1996 electricity demand[in CaU[ornia] has grown by 3o% but supply by only 6%, leaving an energy short[alL.. anticipated to be almost looo MW irl 2 0 0 1 . "

Gary Fernstrom, Pacific

Gas & Electric

III-V$ REVIEW THE ADVANCED SEMICONDUCTOR MAGAZINE VOL t4 - NO t - JAN/FEB 2oat I

MARKET A N A L Y S I S Optoelectronics

34

All olher applications Yellow traffic lights Left turns and lane signals

Green traffic lights 8" and 12" <2% penetration

Red traffic lights 8" and 12" 12% penetration

Figure 3, Spgna/ LED market share, by

ap#tica#ot~.

Crc , s!

pedestrian signs ii

a red LED traffic light in 1994 tn the curreIlt

North Amer ican market pene t ra t ion level of 10%

of lights sold and a total installed base of 350,000

units at the end of 1999 (over 4O% being red

lights anti green anti crosswalk lights about 20%

each - see Figure 3). He forecasts 60% market

pene t ra t ion in North .4merica by 2005.

William Gar tner of Traffic Technology Inc com-

pares the 135 W power consumpt ion of a stan-

dard traffic light versus 16 W for tl~eir Unilight

LED versiot~ and, similarly, 135 ~J~" for the green

turn arrow versus 8 W for the EEl) vers ion .The

LEDs 80-90% reduct ion in power use results in a

U55604~0 annual cost reduct ion pe r light (except

for amber, due to its low duty cycle) and annual

main tenance savings of about US:$2500 per inter-

sectio~a. Garmer sees 24m signals being replaced

by the year 2020 wi th annual savings or"

USS2.5bn or 25m M ~ ~ (equivalent to one p o w e r

Vehicle traffic signals Pedestrian signals Hazard identification beacon (flashing beacons) Lane-use control signals Railroad signals Airfield lighting

Table 2. Primacy light source applications of LEDs.

Pedestrian cross-walk lighting Pavement indication at traffic signal stop Warning lights Variable message signs Highway barrier lighting

Table 3. Supplementary (secondary) light source applications of LEDs.

station). He also quoted Jeff Nelson from Sandia

Nation',d Laboratory as saying that "ff all the mean-

descent and f luorescent bulbs [in the worldl

were replaced wi th LEDs, it could save the equiv-

alent of 38 nuclear power plants." This could start

in about 25 years, based on tile technology

improvements ant icipated for white-l ight LEDs.

Al though traffic signals are current ly the largest

Iraft]c appl icadon for LEDs, Nathaniel Behura of

LEDpro highlights o ther appl icat ions which are

growth market opportuni t ies , b o t h pr imary

sources (Table 2 - most ly g o v c m m e n t regulated)

and secondary sources (Table 3, e.g. pa thway

del ineat ion and warn ing lights - current ly no t as

regulated). Many of these appl icat ions make use

of the ruggedness of LED lighting systems in con-

junct ion with thei r low power demands,

enabl ing some LED-based systems in remote loca-

t ions to be powered by solar cells.

The case has been well d o c u m e n t e d for the traf-

fic markets, bu t general lighting appl icat ions

such as white-l ight p roduc t ion and display signs

p resen t equally large oppor tuni t ies for LEDs.The

market f~)r large ou tdoor signs (2m x 3m a~d

larger) has been growing for several years, espe-

cially since the advent of the blue LED in 1997

enabled the manufac ture of whi te and fl,ll-colour

signs (e.g. the n e w NASDAQ sign in Times Square

New York, w h i c h uses 19m LEDs and covers the

end of a building). O the r rapidly growing uses

are for advanced white-l ighting appl icat ions such

as flashlights and indoor l ighting and for

coloured lighting, l ighting strips and replace-

ments for n e o n lights (cg .Al lnGaP orange and

red high-br ightness LEDs and lnGaN violet, blue,

green and whi t e LEDs).

Apart f rom the USA, there is also significant activ-

ity in bo thAs ia and Europe. Asian use of the large

ou tdoor signs is ahead of Europe and Nor th

America, whi le Japan 's accep tance of traffic sig-

nals is ahead of everybody. Most European coun-

tries art" installing LED traffic lighls, but Sweden

could be leading the pack in novel road applica-

t ions fbr supplementa l lighting. According to Nils

Borg from Borg & Company and Lars Bylund

from Polk Design Group KB in Stockholm, these

include road and footpath markers, traffic i n fo f

mat ion lights and 3 W whi te LED pilot markers

for roads instead of convent iona l lighting, wi th

the potent ial for 60-90% energy savings.There

are n o w roadmaps in Nor th America and Europe

to improve LED produc t ion technology and to

p romote the i r wider use.

IIl-Vs REVIEW THE ADVANCED SEMICONDUCTOR MAGAZINE VOL 14 - NO 1 - JAN/FEB 2002

Optoelectronics

Two auto-related companies have also diversified

into this arena: Uniroyal Technology Corp has

bought the silicon carbide manufacturer Sterling

Semiconductor and has a cooperat ive agreement

be tween Uniroyal Optoelect ronics and EMCORE

(as well as spawning start-up Novalux), while

Toyota has for somet ime held a 41% interest in

nitride-based LED manufacturerToyoda Gosei.

Because of the i r efficiency and potent ia l energy

sa~dngs o n a nat ional scale, the n e w generat ion of

LEDs has not gone unno t i ced by US gove rnmen t

agencies ( including the US Energy D e p a r t m e n t

and the Environmenta l Pollution Agency) and

p o w e r genera t ion companies.Additionally, thei r

long-life, low-power, low-voltage and cool opera-

t ion have made whi t e LEDs popu la r for space

appl icat ions whi le the low p o w e r c o n s u m p t i o n

of co loured LEDs has made the installation of

traffic lights a priori ty to save on peak p o w e r

demands for the electr ic utility companies .

According to Gary Ferns t rom from Pacific Gas &

Electric (California's biggest utility company) ,

some of these rep lacements are s u p p o r t e d by

incent ives f rom the D e p a r t m e n t of Energy and

the p o w e r companies , w i th US$36m available in

California for LED traffic signal installation. In the

Nor the rn California PG&E region alone, h e esti-

mates tha t 5 MW would be saved if 50% of the

signals were changed to LED units; worldwide,

hund reds of megawat ts could be saved.

Ferns t rom notes tha t ene rgy saving has b e c o m e

very i m p o r t a n t in many states of the USA,

including California w h e r e - s ince deregula t ion

in 1996 - electr ici ty d e m a n d has g r o w n by 30%

bu t supply by only 6%, leaving an energy short-

fall ( including even win te r p o w e r shor tage

alerts) .This is an t ic ipa ted to b e a lmost 1000 MW

in 2001, in par t caused by recen t h i d d e n stand-by

uses for always-on i tems such as c o m p u t e r s and

househo ld appliances, plus a r ecen t display~

mania for l ighted soft-drink machines .This short-

age is also causing some n e w rules to be pro-

posed, such as l imit ing all exit signs sold in

California to a rat ing of 5 W or less, eventually

saving 10 MW - more if LEDs are used (as wel l as

reduc ing ma in t enance costs and improving safe-

ty, s ince they do no t in general suffer catastroph-

ic failures like a b l o w n l ight bulb). Such a prece-

den t would represen t very significant savings if

fol lowed by the rest of the world.

According to Rachel Schmeltz f rom the US

Environmenta l Pollution Agency, one aspect

of thei r Energy Star efficiency p rogramme to

°° I "° 40

E t -

~ 20

s s . ( l ~

s ~ v s "

s s

s o

100 mA (dc), Ta=300 K

0~905 1 I 1 610 630 650

Peak wavelength (nm)

promote LED signs has b e e n rated a resounding

success .The paybacks are less than one year and

provide a reduct ion in ca rbon emissions.A 75%

energy reduct ion in n e w exit signs results in ann-

ual savings of 2bn kW-hr.The US G o v e r n m e n t has

required Energy Star labelled p roduc ts to b e used

since 1999, but many states in the USA still have

to formally adopt the p rogramme ( w h i c h also

includes specifications for o ther traffic signals).

Reviewing the l ineage of the high-br ighmcss LED,

George Cr~aford of LumiLeds reckons that the

cost pe r lumen of the lowly red LED ( w h i c h

began life in 1960) has improved lO-fold for

every decade - f rom less than O. 1 lumen/Wat t to

the bes t red and orange LEDs n o w providing

about 100 I /~ .The red LED has been a real suc-

cess story, w h e r e - pe r decade - the light o u t p u t

has increased 30-fold pe r decade.

Significantly, the light genera t ion efficiency of

these s in#e-source LED chips has improved to

w h e r e today's q u a n t u m efficiencies are very h igh

so tha t the main engineer ing chal lenge is n o w

the extract ion efficiency, or the ability to get all

the l ight out of the chip to w h e r e it is needed.

This has led to novel changes in the shape of the

LED chip and to the r ep lacemen t of the gallium

arsenide p roduc t ion wafer wi th t ransparen t galli-

u m p h o s p h i d e ( th rough wafer bond ing after the

LED has b e e n produced , as in the case of the

high-br ightness orange LEDs). By using a "truncat-

ed-inverted-pyramid" design (see Figure 2), the

externa l q u a n t u m efficiencies n o w exceed 50%

for the orange LEDs so that more than 120

lumens can be ext rac ted from one chip on a

pulsed o u t p u t basis.

According to Henry Arcand of Ecolux Inc (now a

subsidiary of GELcore) the market for LED traffic

lights has p rogressed f rom the first instal lat ion of

Figure 2. AIInGaP/GaP truncated-inverted-pyramid (TIP) LEDs.

"Since deregulation in 1996 electricity demand[in Colifornio] hos grown by 3o% but supply by only 6%, leaving an energy shortfalL.. anticipated to be almost looo MW in 2oo1." Gary Fernstrom, Pacific

Gas & Electric

IIl-Vs REVIEW THE ADVANCED SEMICONDUCTOR MAGAZINE VOL t4 - NO t - JAN/FEB 2oot B

34

Optoelectronics

All other applications Yellow traffic lights Left turns and lane signals

Green traffic lights 8" and 12" <2% penetration

Red traffic lights 8" and 12" 12% penetration

Cros: pedestrian signs

Figure 3. Signal LED market share, by

application.

a red LED traffic light in 1994 to the current

North American market penetrat ion level of 10%

of lights sold and a total installed base of 350,000

units at the end of 1999 (over 40% being red

lights and green and crosswalk lights about 20%

each - see Figure 3). He forecasts 60% market

penetrat ion in North America by 2005.

William Gartner of Traffic Technology Inc com-

pares the 135 W power consumption of a stan-

dard traffic light versus 16 W for their Unilight

LED version and, similarly, 135 W for the green

turn arrow versus 8 W for the LED version.The

LEDs 80-90% reduction in power use results in a

US$60-80 annual cost reduction per light (except

for amber, due to its low duty cycle) and annual

maintenance savings of about US$2500 per inter-

section. Gartner sees 24m signals being replaced

by the year 2020 with annual savings of

US$2.5bn or 25m MW (equivalent to one power

Vehicle traffic signals Pedestrian signals Hazard identification beacon (flashing beacons) Lane-use control signals Railroad signals Airfield lighting

Table 2. Primary light source applications of LEDs.

Pedestrian cross-walk lighting Pavement indication at traffic signal stop Warning lights Variable message signs Highway barrier lighting

Table 3. Supplementary (secondary) light source applications of LEDs.

station). He also quoted Jeff Nelson from Sandia

National Laboratory as saying that "if all the incan-

descent and fluorescent bulbs [in the world]

were replaced with LEDs, it could save the equiv-

alent of 38 nuclear power plants." This could start

in about 25 years, based on the technology

improvements anticipated for white-light LEDs.

Although traffic signals are currently the largest

traffic application for LEDs, Nathaniel Behura of

LEDpro highlights other applications which are

growth market opportunities, both primary

sources (Table 2 - mostly government regulated)

and secondary sources (Table 3, e.g. pathway

delineation and warning lights - currently not as

regulated). Many of these applications make use

of the ruggedness of LED lighting systems in con-

junction with their low power demands,

enabling some LED-based systems in remote loca-

tions to be powered by solar cells.

The case has been well documented for the traf-

fic markets, but general lighting applications

such as white-light product ion and display signs

present equally large opportunit ies for LEDs.The

market for large outdoor signs (2m x 3m and

larger) has been growing for several years, espe-

cially since the advent of the blue LED in 1997

enabled the manufacture of whi te and full-colour

signs (e.g. the n e w NASDAQ sign inTimes Square

NewYork, which uses 19m LEDs and covers the

end of a building). Other rapidly growing uses

are for advanced white-lighting applications such

as flashlights and indoor lighting and for

coloured lighting, lighting strips and replace-

ments for neon lights (e.g.AllnGaP orange and

red high-brightness LEDs and InGaN violet, blue,

green and whi te LEDs).

Apart from the USA, there is also significant activ-

ity in both Asia and Europe.Asian use of the large

outdoor signs is ahead of Europe and North

America, while Japan's acceptance of traffic sig-

nals is ahead of everybody. Most European coun-

tries are installing LED traffic lights, but Sweden

could be leading the pack in novel road applica-

tions for supplemental l ighting.According to Nils

Borg from Borg & Company and Lars Bylund

from Pelk Design Group KB in Stockholm, these

include road and footpath markers, traffic infor-

mation lights and 3 W whi te LED pilot markers

for roads instead of conventional lighting, wi th

the potential for 60-90% energy savings.There

are n o w roadmaps in North America and Europe

to improve LED product ion technology and to

promote their wider use.

III-Vs REVIEW THE ADVANCED SEMICONDUCTOR MAGAZINE VOL 14 - NO 1 - JAN/FEB 2ool

Optoelectronics

According to Bernd Keller of GaN LED manufac-

turer Cree Lighting Company, only the traffic light

and large-sign applications can currently be con-

sidered volume markets. Other applications may

have large market potential but are at the stage of

technology development and mostly restricted to

speciality, markets by the current high cost per

lumen of the available light. However, as manufac-

turing technology advances and the costs per

lumen are reduced, growth rates will increase.

(A similar situation also holds for GaN-based high-

temperature and high-power electronics.)

As Cree Inc is also a manufacturer of silicon car-

bide substrates, it is not surprising that their

LEDs use this substrate, which is deemed to have

advantages for electrical and heat conductivity.

However, recent measurements of higher GaN

thermal conductivity may nullify some of these

advantages (see ISCS report, this issue, page 28).

The advantages of GaN-based LEDs are high effi-

ciency, high light output and long life.Also, they

can operate at high materials temperatures. New

performance records are continually being

repor ted for GaN devices, and most are a further

step toward n e w applications. However, Keller

repor ted a recent world record that is wor thy of

note: that the 28% quantum and 21% wall-plug

efficiency from a near-ultra-violet diode and the

output of large-area pulsed LEDs illustrate the

potential for practical applications (see Figure 4).

This is very significant because these LEDs are

the foundation of the phosphor-conver ted whi te

light emit ters that are expec ted to challenge

incandescent lighting in the distant future. For

the time being, whi te LEDs have to be satisfied

wi th smaller volume markets such as flashlights

and back-lighting applications.

The creation of the blue LED and its growing list

of applications (including the large, outdoor full-

colour signs and white LED products) was enabled

by the original commitment of Nichia, the world's

leading supplier of blue LEDs, which now also

offers green LEDs for traffic lights and phosphor-

based white LEDs for general lighting.According to

Naoki Yoshida of Nichia America Corp, their con-

tinuing development of GaN LEDs includes a large

research programme for the development of other

InGaN single quantum well LED products, includ-

ing amber lights and the recently announced yel-

low LED based on their phosphor technology.

Nichia also leads the world in the field of blue

and violet solid-state lasers (which are basically

overdriven LEDs).These have the potential to

2.0

~" 1.5 {u

0

a_ 0,5

0(~ 1 2

25 W incandescent P UV + visible photons /

Current (Amps)

revolutionise the DVD market by quadrupling

the disc capacity and opening up markets for

other optoelect ronic products. Since the technol-

ogy merits of GaN LEDs are n o w not in doubt,

time is the controlling factor for their wider

acceptance in many world markets.

Last but not least, some LED applications that do

not receive as much publicity were highlighted

by Manfred Hubert from EFOS Inc, which deals

mainly in the UV and infrared curing of inks and

coatings on man}" surfaces and e m b w o n i c med-

ical LED uses including laser therapy, photo-bios-

timulation and f luorescence diagnostics.

Wavelengths used for these processes range from

200-900 nm, most of which (except for short-

wavelength loW) is immediately accessible to

LEDs.Arrays ofAlGaAs LEDs have been devel-

oped for skin radiation therapy, and biostimula-

tion cures by wavelength-specific LED radiation

are being evaluated for skin ailments, including

some cancers. LEDs are ideal light sources for

these types of t reatments because of their small

size and because it is normally not too difficult

to match an LED output to the peak absorption

wavelength of the drug being applied.As these

treatments receive approval from the medical

regulatory authorities, high unit volumes of these

LEDs may be required.

With such a positive outlook in so many applica-

tion fields, there must be no doubt in many

minds that LED businesses are the place to be.

This certainly seemed to be the outlook of the

vendors present at the LED-2000 conference, and

this sent iment was spread across the business

spectrum; from the traffic signal manufacturers,

to the white- and coloured-light fixture makers,

to LED key-chain makers, to the LED manufactur-

ing and test equ ipment suppliers, the wafer and

process chemical suppliers and, of course, to the

LED chip makers themselves.

Figure 4. Peak power out- put vs current for high- power large-area LEDs. Pulsed operation shows fundamental capabilities of GaN: 1.2 W output power of UV light at 9 W input power is possible.

"If all the

incandescent

and tluorescent

bulbs [in the

world] were

replaced with

LEDs, it could

save the

equivalent of 38

nuclear power

plants." left" Neiso~, Sandia

Nationat Laborator,¢

"This could start

in about 25

years, based on

the technology

improvements

anticipated for

white-light

LEDs. " WilJiam Gartneh Traffic Techology

I I I-Vs REVIEW ~ i ~ >~,~ ~ ~ ~ i ~ ,A,, ~i VOL 14 - NO 1 - JAN/FEB 2ool 37