Engineers in the US have created solid, crystalline quantum dot structures made of exceedingly small particles. Because these structures are so near to perfection, they might be a genuine competitor to replace silicon in future super-fast computers.
Quantum dot solids have the potential to fundamentally alter
how we communicate and process information in the next decades, much as
single-crystal silicon wafers did more than 60 years ago (without one, your
phone, laptop, PC, and iPad would not exist).
Although quantum dot crystals offer enormous promise for use
in computing, researchers have struggled for years to organize each individual
dot into a precisely organized solid, which is necessary if you want to put it
in a processor and send an electric charge through it.
The issue? Since quantum dots only contain 5,000 atoms
apiece, previous attempts to construct something out of them have failed since
scientists were unable to find out a way to 'glue' them together without
utilizing a different substance that interferes with their function.
According to Cornell University's main researcher Tobias
Hanrath, "before, they were basically tossed together, and you hoped for
the best." "It was like trying to get power flowing from one end of a
bathtub full of batteries," one person said.
Hanrath and his colleagues have discovered a way to do away
with the glue and adhere the quantum dots to each other, Lego-style, rather
than exploring various chemicals and materials that may serve as the
"glue," but impair the quantum dot's electrical capabilities.
Hanrath claims that if multiple quantum dots of exactly the
same size are thrown together, they will naturally align into a larger crystal.
To do this, the scientists first created lead and selenium
nanocrystals and then assembled them into crystalline pieces. These pieces were
then combined to create two-dimensional, square-shaped
"superstructures" that function as microscopic building blocks that
connect to one another devoid of the aid of additional atoms.
The team claims in a paper published in Nature Materials that
the electrical characteristics of these superstructures may be superior to
those of all other semiconductor nanocrystals currently in use, and they may be
used in novel types of devices for extremely effective energy absorption and
light emission.
However, the imperfection of the structures is a significant
drawback of employing quantum dots as your building blocks. Each quantum dot
can vary in size by around 5%, but every silicon atom is exactly the same size.
Even when we're talking about a few thousand atoms tiny, that 5% size
fluctuation is enough to prohibit perfection.
Hanrath claims that this is both a good and a terrible
thing—good because they were able to push the boundaries of what is possible
with quantum dot solids, but bad because they did.
According to a news release, "that's the equivalent of
saying, "Now we've built a tremendously enormous single-crystal wafer of
silicon, and you can do nice things with it." That's the positive aspect,
but the possibly negative aspect is that we now have a greater grasp of how
difficult it would be to improve upon current outcomes.
One of the team members, Kevin Whitham, says, "I see
this study as somewhat of a challenge for future researchers to take this to
another level." "This is as far as we can push it at the moment, but
if someone were to come up with some technology or some chemistry to make
another leap ahead, this is kind of daring other people to say, "How can
we do this better?"
That is the definition of "Game on, fellow
engineers" in my book. Defeat the world!
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