
Carbon Nanotubes Finally Outperform Silicon in Transistors - xd
http://www.allaboutcircuits.com/news/end-of-mosfets-carbon-nanotubes-finally-outperform-silicon-in-transistors/
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ChuckMcM
I don't doubt that eventually our chips will be structured carbon circuits on
a diamond substrate. I find it amusing that should a sentient AI arise post
transition, it could reasonably think of itself as a carbon based life form
:-).

The question I have not seen addressed is how we'll pattern the circuits. The
ability to convert silicon into N-type and P-type material by doping is so
"simple" compared to trying to induce the formation of CNTs of a particular
geometry with the precision needed to develop a particular circuit. We are at
the 'Bell labs' point where we can make individual (and volumetrically large)
transistors out of CNTs or Graphene. But as we know from history, the
revolution didn't really get underway until we could pattern a complete
circuit on a substrate in the form of an integrated circuit. I'm still
watching for the folks who come up with that breakthrough.

~~~
Florin_Andrei
> _I find it amusing that should a sentient AI arise post transition, it could
> reasonably think of itself as a carbon based life form_

The best of everything (X) ends up carbon-based. Life forms, computers, space
towers, etc. It's just due to the carbon atom having a bunch of unusual
properties.

(X) - whereas "everything" is an exaggeration used to make a point

~~~
Razengan
I'm not sure if that sentiment isn't carbon chauvinism, given that the best
_we know so far_ has been carbon-based.

I'm sure the universe in its infinity has plenty of surprises in store for an
species that has yet to leave their home planet.

~~~
wtallis
There's no reason to expect far-flung corners of the universe to have
different chemistry. We already know what the periodic table is for those
unexplored regions of space, and they don't have anything cheaper and more
versatile than carbon.

~~~
mcbits
Maybe I'm underestimating the field, but I suspect there is still a lot to
learn about chemistry in extreme environments (ultra hot, dense, etc), which
would be most of the universe. Some experimentation is possible on Earth, but
how much could we really learn about, say, liquid water if all we could
produce were a few molecules in very restricted environments? I guess that's
all kind of irrelevant until we're ready to try building transistors inside
the Sun.

~~~
wtallis
We already know enough about chemistry and physics to rule out the possibility
of building transistors inside the sun, or any other useful permanent
structure inside a star. At the opposite end of the spectrum, we're already
commercially exploiting temperatures on par with deep space and extremely low
pressures. Yes, there's a lot we don't know about the properties of things or
conditions that are hard to keep around in large quantities in the lab. But
we're not going to discover complex life or be able to engineer complex and
cost-effective machines in conditions where there's so much energy that
molecular bonds can't stay intact or where there's so little energy that
nothing gets done at better than a glacial pace. There's surely interesting
stuff left to be discovered in those fields, but we won't magically stumble
across a plasma-based computing substrate that is better than what we can
already do on Earth.

~~~
marcosdumay
I'm not this confident on our knowledge of the high pressure environments
inside stars.

We can rule-out unexpected simple chemistry on other planets and in the outer
space, but the inside of stars is too different an environment.

Also, we surely can not rule-out anything from complex chemistry on any kind
of environment. Macromolecules and non-repeating crystals are very badly
understood.

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Symmetry
I'm sure that people will be able to create very fast carbon nanotube
transistors (CNTFETs) in the future but that isn't currently the problem.
Generally when you're creating normal silicon transistors (MOSFETs) one out of
every billion or so is bad, meaning you have to fuse off some block of cache
or maybe an entire core but multi-billion transistor chips are possible when
you do stuff like that.

My understanding of the state of the art of CNTFETs right now is that only
having one out of every 10 be bad would be a significant advance. So making 10
transistor circuits is maybe feasible but nothing larger. And even the 8086
had 20,000 transistors.

There's a lot of work that has to be done before CNTFETs are ready to be used
in computers.

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nutschig
Silicon is not the best transistor material ever. For example, gallium
arsenide can run at a switching frequency of 250 GHz thanks to faster electron
velocity and higher electron mobility.
[https://en.wikipedia.org/wiki/Gallium_arsenide#GaAs_advantag...](https://en.wikipedia.org/wiki/Gallium_arsenide#GaAs_advantages)

~~~
GregBuchholz
You can create some pretty high frequency transistors (BJTs) with Indium
Phosphide (InP) (ft > 600GHz, fmax > 1THz). See page 33 of:

[http://www.ece.ucsb.edu/Faculty/rodwell/publications_and_pre...](http://www.ece.ucsb.edu/Faculty/rodwell/publications_and_presentations/publications/2012_10_15_Oct_rodwell_CSIC_talk.pdf)

...for examples of some 600 GHz circuits, and:

[http://www.semiconductor-
today.com/news_items/2014/OCT/NORTH...](http://www.semiconductor-
today.com/news_items/2014/OCT/NORTHROP-GRUMMAN_311014.shtml)

...for a >1THz circuit using InP HEMTs.

~~~
raverbashing
Wow that's crazy.

I wonder how you even test a 1THz amplifier. Also what kind of natural noise
might exist in those bands

~~~
GregBuchholz
>I wonder how you even test a 1THz amplifier.

Most likely using a mixer or some other non-linearity to down convert into the
frequency range of your spectrum analyzer.

~~~
raverbashing
And how do you get the 1THz signal in the 1st place? Maybe upconvert as well?

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wav-part
Paper :
[http://advances.sciencemag.org/content/advances/2/9/e1601240...](http://advances.sciencemag.org/content/advances/2/9/e1601240.full.pdf)

Previous Discussion :
[https://news.ycombinator.com/item?id=12429779](https://news.ycombinator.com/item?id=12429779)
(39 days ago, 42 comments)

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traviswingo
This is a really important advancement in circuits. We were reaching the
physical limits of silicon and it was only a matter of time before we would
have to find an alternative to continue the upward trends of transistor
performance.

~~~
GregBuchholz
There are quite a few materials which outperform straight silicon, but it is
hard to compete with the gigantic amount of existing silicon infrastructure,
except for very niche applications.

[https://en.wikipedia.org/wiki/High-electron-
mobility_transis...](https://en.wikipedia.org/wiki/High-electron-
mobility_transistor)

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madengr
I thought it was innterconnect loss and heat dissipation that is keeping
processor clocks slow, not intrinsic transistor speed.

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mankash666
Even if the science becomes feasible, this domain in encumbered with too many
patents.

~~~
happycube
That'd explain why the military is funding it - patents don't apply to them!

