Blue LED's: breakthroughs & implications

[David Farber <farber () central cis upenn edu>]

       ASIAN TECHNOLOGY INFORMATION PROGRAM (ATIP)


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ATIP95.59 : Blue LED's: breakthroughs & implications


ABSTRACT: Very bright blue light emitting diodes (LED's) have recently been
developed and made commercially available by Nichia Chemical in Japan.
Efficient red, yellow and green LED's already exist, and are used in
displays such as in the Tokyo subway. However with these existing LED's
full color displays were not possible. The newly developed blue LED's fill
this gap. We expect that they will be used to replace traffic signals. Other
expected applications for blue LED's will be full color scanners, displays,
and possibly even commercial and residential lighting. This report
discusses this new technology, its potential applications and markets.
Because of the very considerable commercial importance of blue/green, blue
and violet LED's, most multinationals in the electronics field, many
universities, and many national laboratories have substantial research
efforts in this area. This report also discusses why Nichia, a relatively
small company, won this race with a comparatively small project budget and
one single researcher helped by a few assistants, against other major
electronics multinationals. A world-wide race is now on, to develop the
first commercially viable blue laser, which is expected to have extremely
important applications, for example in optical data storage.


=====================START OF REPORT ATIP95.59===========================


Blue light emitters for displays, scanners, data storage, and traffic signals
     Recent Breakthroughs by Nichia Chemical Industries Ltd.,
              Background and Implications
        (Prof Gerhard Fasol, University of Tokyo)


CONTENTS:


0.  OVERVIEW
1.  INTRODUCTION
2.  APPLICATIONS AND MARKETS FOR BLUE LED'S
       Table 1: Comparison of Red, Green and Blue LED's
       Table 2: Comparison of light bulbs and light emitting diodes (LED's)
                 for application in traffic lights and railway signals
3.  WHO ARE THE EARLY KEY PLAYERS IN THE FIELD?
       Table 3: Who are some early key players in the field?
                Typical US Patents in the Gallium-Nitride field '93-'95
5.  WHY INDIUM-GALLIUM-NITRIDE/ALUMINUM-GALLIUM-NITRIDE?
6.  KEY STEPS IN THE DISCOVERY - MATERIALS ISSUES
       Table 4: Layer sequence of Nichia's blue GaN LED's
       Table 5: Research history of S. Nakamura and selected steps
                 in the development of the commercial blue GaN LED
7.  WHY DID NICHIA SUCCEED WHERE OTHERS FAILED?
       Table 6. Nichia : Annual Sales and Number of Employees '83-'94
       Table 7: Nichia Group's Slogan
8.  ADDITIONAL COMMENTS ON BLUE LED RESEARCH.
9.  FUTURE.
10. SUMMARY.
11. SELECTED REFERENCES
12  CONTACT




====================


0. OVERVIEW.


Nichia Chemical Industries Ltd. (Anan, Tokushima-ken, Japan)  has
recently developed blue and blue/green light emitting diodes (LED's)
using Indium-Gallium-Nitride and Aluminum-Gallium-Nitride compounds.
Nichia's blue (peak wavelength 450 nm) LED's are about 100 times
brighter than the previously available blue Silicon-Carbide based blue
LED's. Nichia's blue LED's are now in commercial service in large
outdoor television displays (for example at Hachiko-square in
Tokyo-Shibuya), Nichia employs about 100 people commercially producing
blue LED's and sells at present (June 1995) about 1 to 2 Million blue
LED's per month.


It is likely that blue LED's will replace traffic lights, because the
energy saving is expected to be about 50% to 75%, replacement intervals
will be 5 - 10 years instead of presently once per year for traffic
light bulbs in Japan. Instead of sudden total darkness, when the
filament of a light bulb breaks, for blue GaN LED's the light intensity
decreases gradually with a half-life of the order of 5 to 10 years.
Other expected applications for blue LED's  will be full color scanners,
displays, and possibly even lighting applications.


Because of the very considerable commercial importance of blue/green,
blue and violet light emitters most multinationals in the electronics
field, many universities, and many national laboratories had and have
substantial research efforts in this area.  It is also an aim of the
present report to discuss, why Nichia Chemical Industries, a relatively
small company, won this race with a comparatively small project budget
and one single researcher (Nakamura) helped by a few assistants, against
most major electronics multinationals with incomparably larger total
research resources.


Nichia Chemical Industries Ltd. is based in Anan, Tokushima-ken, Japan,
has annual sales of US$222 Million in 1994, 750 Employees (of which 30
in R&D). It is a privately held stock company: 23% of shares are owned
by the Directors, 27% by the employees, and 50% by others. Nichia's
products are specialty chemicals, ceramics and related products. Nichia
has 50% of the Japanese market and 25% of the world wide market in the
phosphor coating of cathode ray display tubes (as used for TV sets,
computer monitors, X-ray monitors, oscilloscopes etc) and of fluorescent
light tubes.


There is a world-wide race to develop the first GaN based blue laser,
which is expected to have extremely important applications, for example
in optical data storage.






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=====================END OF REPORT ATIP95.59a===========================
 [The following sections of this report are available to ATIP subscribers]