The blue LED. You may consider it a pretty mundane aspect
of modern life, largely relegated to simple tasks such as indicating power and illuminating
holiday lights. Ubiquitous as they are now though, they’re
a relatively recent invention, and until 1993 there was no such thing as a commercially
viable blue LED. Yet without them so much of our modern tech
would not be possible, from cell phone displays, to energy-efficient light bulbs, to that blue-lit button on the front of your toaster. Blue LEDs were such an important advancement that inventors behind it were awarded the Nobel Prize in 2014. What happened? This is LGR Tech Tales, where we take a look
at noteworthy stories of technological inspiration, failure, and everything in-between. This episode tells the tale of the decades-long
struggle to create the blue LED. Our story begins in 1907 with the emergence
of the light-emitting diode. Henry Joseph Round discovered that if you
touch two metal needles to a crystal of silicon carbide and apply electricity, you’d sometimes
see a very dim light glowing color. Silicon carbide, while often used in things
like sandpaper, is actually a semiconducting material, and the electrified needles created
a diode, hence: light-emitting diode, or LED is what it was called. But while this was experimented with for years,
including notable examples by Oleg Losev in Russia in the 1920s, it took decades for
a practical LED to be produced. An important step in this direction came from Dr. Rubin Braunstein
at RCA in 1955 that showed an infrared emission from semiconductor alloys like gallium arsenide. This was followed up in 1961 at Texas Instruments
by James Biard and Gary Pittman, who discovered a 900nm near-infrared light emission on a
gallium substrate. The same method would also be used at General Electric to create a more visible LED
through the work of Nick Holonyak Jr. His diode showed a defined, yet faint,
red light visible to the naked eye. Over the next decade, various chemical compositions
were used to produce yellow and green LEDs as well, which in turn helped inform the future improvement of the others. These red-orange LEDs proved to be some of
the brightest and most cost-effective to manufacture, initially sold to the military and companies
like Hewlett Packard, before appearing in consumer products like the pocket calculators
of the early 1970s. Soon, LEDs were popping up in electronics
all over the place, finding uses in everything from computer displays, to telephone keypad lighting. However, there was still a primary color that
remained elusive. Blue. The idea of a blue LED was highly desirable
since blue light is a crucial part of producing a full spectrum of color. The three additive primary colors of red,
green, and blue can be mixed to create other colors between them, and then combine completely
to create white. And the reason LEDs were stuck with various
hues of red, yellow, and green, but not blue, is down to the physics in how light is produced
on a diode to begin with. To put it very simply, an LED is made up of multiple
layers of positive and negative semiconductor materials, and when electricity passes through them, they emit
light at the frequency the materials allow. In order to achieve a specific color and brightness,
each LED needs precisely the right configuration of materials on the semiconductor die. And since the frequency interval of blue light
is much higher than red, yellow, and even green, it required far more exotic materials and
production processes to reproduce. Some of the early blue LEDs were developed
at RCA in 1972, while attempting to come up with a television that used LEDs instead of
phosphors in cathode ray tubes. That breakthrough was achieved at RCA that year
by Herbert Maruska, accomplished by first figuring out how to grow crystals of gallium
nitride, and then “doping” them with magnesium. But unfortunately
the resulting light was too dim to be practical, and seeing as RCA was in financial trouble
going into the mid-70s, further development was halted. So, gallium nitride and magnesium. The groundwork was there, but there were huge
obstacles to overcome to make this light bright enough to be useful and cheap enough to be
practical. Companies like Bell Labs and Matsushita continued
working with these materials for years, before coming to the conclusion that gallium nitride
was unlikely to result in viable blue LEDs since it was so tough to work with. Growing the crystals in high enough quality
and quantity was stupidly challenging, and reliably producing the exact types of positive
and negative layers required was even harder. It was not until the 1980s that these obstacles
would be overcome, and it was largely thanks to a string of breakthroughs by three
men in Japan. The first is Isamu Akasaki, who was a physicist
at Nagoya University leading a group in coming up with a better method of growing gallium
nitride. Next is Hiroshi Amano, an undergraduate researching
the growth of nitride semiconductors, who joined Akasaki’s group in 1982. And finally we have Shuji Nakamura, an electronic
engineer specializing in semiconductor tech at the Nichia Corporation in Tokushima. It was in 1985 that Amano first had promising
results in making high quality gallium nitride by using what the team called ‘low-temperature
buffer layer technology.’ This was an important step to growing high
quality crystals, but it didn’t solve the problem of producing an efficient positive
and negative junction. That didn’t happen until 1989, when Akasaki’s
group finally succeeded in fabricating the correct layers by irradiating the crystals
with a high-powered electron beam. The results still were too complicated and
costly to be used commercially, but the results and the research were made available for people
to read. People like Shuji Nakamura, who was working
on creating new products for the Nichia Corporation. At the time, Nichia was known for producing
phosphors used in fluorescent lights and color cathode ray tubes, but were looking for a
fresh new product with fewer competitors. Nakamura was already working on projects involving
gallium phosphorus for the company when Akasaki’s group announced their method of creating high
quality gallium nitride. And Nakamura took note. He asked for permission to pursue the creation
even better quality gallium nitride for Nichia, at a cost of five hundred million yen; which was about
two percent of the entire company's sales that year. It was a massive amount indeed, but they granted
him permission and the work began. The first breakthrough came by using thermal
annealing instead of an electron beam, which resulted in a higher quality LED but also
appeared more violet than it did blue. Another thing he did was create a double heterostructure,
basically a sandwich of iridium-infused gallium nitride and the existing GaN crystals, which
narrowed the bandwidth of the light to appear blue and was tweaked to help create a brighter
LED. Finally on November 29, 1993, Nichia Corporation
and Nakamura made public their version of the blue LED, one that was a hundred times
brighter and more vivid than those of the past. And it was affordable to create! So Nichia put it into production immediately,
and Nakamura continued to work on the project, doubling the brightness of their blue LED in
May of 1994. Logically following blue were high-intensity
white LEDs in 1995, produced by adding a yellow phosphor to the blue diode, converting its
sky blue light to a vivid white. Other companies began to follow suit and started producing
their own versions of blue LEDs, and what resulted was an explosion of LED usage. Now we finally
had the full color spectrum through LEDs, and they’re used in everything from home
appliances, to televisions screens and backlighting, to cell phone and tablet displays. And the altered blue LEDs that result in white
light have created a revolution of sorts in general lighting applications by being far more energy
efficient and longer-lasting alternatives to incandescent and fluorescent bulbs. Not to mention home lightning is more versatile
and colorful than ever, with RGB LEDs combining to create vivid displays in everything from
mood lighting bulbs to gaming keyboards. Another advancement birthed from the blue
LED arrived in 1996, where Nakamura built on his work to produce the first efficient
blue laser. While it took some time for the effects of blue LEDs to really be noticed, the benefit of a blue laser was immediate
cause for excitement within the data storage community. Up to that point, lasers for media storage
were only available in red, and their lower wavelength meant you could only store so much
data on things like CDs and DVDs. But with blue lasers, or more accurately blue-violet
in this case, the potential for higher capacity optical media was huge. Blu-ray discs are perhaps the most well-known application
for blue-violet lasers, but they’re also used in plenty of video projectors, telecommunications
devices, and medical diagnostic equipment. But while there’s always more to talk about on a subject like this,
that’s all for this video regarding the blue LED and the struggle to bring it to life. Without them, we wouldn’t have nearly the
same devices and technology in the 21st century that we do. From smartphones to street lamps, from toasters
to headlights. There are few pieces of tech today that haven’t
been affected by the blue LED in some way, so it’s little wonder that Akasaki, Amano,
and Nakamura were awarded the Nobel Prize in Physics 2014 for their creations. At the same time, it’s important to remember
the decades-long mission to invent the blue LED, spread across countless researchers,
companies, and events over the course of the 20th century. Technological breakthroughs rarely happen
in a bubble, and the creation of blue LEDs is very much a worldwide story of success
that only happened through years of failure, persistence, iteration, collaboration,
and hardcore science. And if enjoyed this episode of Tech Tales and my very genuine attempts to pronounce names and scientific terms that I don't say out loud every day, then perhaps you'd like to watch some of my others. And there are other videos going up every Monday and Friday here on LGR. And as always, thank you very much for watching!
I remember the first time I saw a set of speakers with a blue LED power indicator. I freaked out.
Back when blue LEDs exploded onto the market I was at a hifi show. It was a blinding experience.
I have a fetish for blue LED lighting for some reason. Apparently blinding for some, but it looks both calming and badass to me. Not sure how much of that is personal preference or science.
I don't like blue LEDs, I'm not sure why but they look blurry to me, hard for my eyes to focus on them.