UCLA claims 300-GHz graphene transistors (opens in new tab)

(edn.com)

36 pointsrexyo15y ago9 comments

9 comments

4 comments · 2 top-level

jacquesm15y ago· 2 in thread

Light will travel about a millimeter in the time it takes these transistors to switch, how will this be practical?

How would it be... impractical? That means light goes ~ 7,000 times further than the width of the gate (140 nanometer ones have been made) in the same time span. They're hardly pushing any theoretical limits as pertain to the speed of light.

(light speed / 300 billion hertz) * (1 billion nanometers per meter / 140nm) = 7,137.91567 , according to Google's calculator.

jacquesm15y ago

It's a problem because in chip therms that is tiny, and you still need to interface to the outside world, using regular wiring you're much slower than 300GHz, and using optics you have a pretty serious interfacing issue.

Of course even a 10-fold practical increase would be an amazing thing, but I just can't see the 300GHz ever becoming a reality given the constraints that physics imposes on this.

2 more replies

pjscott15y ago

Note that just because someone's invented transistors that can switch at 300 GHz, doesn't mean that you can make a processor which will be able to run with a 300 GHz clock speed. These are two completely different issues, and articles with things like "300 GHZ!" in the headlines often play off this confusion to get page views.

There are already transistors which can switch at much higher frequencies. They're mainly used in radio communications. The promise of graphene semiconductors is that they may be a way of replacing or supplementing silicon, so it's nice that graphene transistors are turning out to have good performance, but the really big issue continues to be figuring out how to mass-produce non-trivial devices. Or even trivial ones.

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