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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 [email protected]
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