IBM Shows 155GHz Graphene Transistor

Get ready for some really fast radios.

IBM has reached a new milestone in its research of graphene transistors. We learned over a year ago that IBM had achieved a radio-frequency graphene transistor with the cut-off frequency of 100 GHz. Now IBM has cranked it up even higher – hitting 155 GHz.

Graphene is a single atom-thick layer of carbon atoms bonded in a hexagonal honeycomb-like arrangement. This two-dimensional form of carbon has unique electrical, optical, mechanical and thermal properties and its technological applications are being explored intensely by IBM.

While the 155 GHz number is mighty impressive, it's not really the sort of transistor that's going to be immediately of interest to those looking for the next big personal computing technology.

IBM's work on the graphene transistor is part of the DARPA program to develop high performance radio transistors. Graphene is better suited to analog signals, as it does not have the discrete on/off characteristics of silicon.

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WyomingKnott , April 12, 2011 7:49 PM

Quote:
... as it does not have the discrete on/off characteristics of silicon.

Someone enlighten me here. I thought that transistors were originally analog devices for many years. They had to be re-designed to be on-off devices. Am I wrong?
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galland , April 12, 2011 8:03 PM

You're right, today's transistors are like a faucet that is used only at full close or full open but still have many intermediate positions
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dogman_1234 , April 12, 2011 8:39 PM

I thought the transistor was suppose to be an on/off switch? I congratulate the engineers at IBM, yet the transistor itself is not all that complete.
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hoofhearted , April 12, 2011 8:41 PM

Can we communicate with Aliens on their radio frequencies now?
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TeraMedia , April 12, 2011 9:35 PM

I wonder how small these things are. Graphene is a single-layer sheet of carbon like the article says, but you can stack layers on top of each other like a pile of paper. Is the transistor based on just a single layer, and if so, what surface area is required? Even a transistor involving 10 hexagons in each direction would only have dimensions of 2.46 nm on a side (one carbon bound is 1.42 Angstroms, and there are sqrt(3) bond-lengths per hexagon).
Unfortunately it sounds like these are more akin to bipolar transistors than cmos in terms of their electrical characteristics, so the amount of current required to turn and keep one "on" rather than "off" would be prohibitive on a chip-wide scale. But if I wanted a radio with a 3mm wavelength, these could be used in the amplifier circuit if the gain is high enough.
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spiketheaardvark , April 12, 2011 11:05 PM

one comment
TeraMediaI wonder how small these things are. .

The advantages of graphene do not come from transistor size but the fact that it's a superconductor at normal temps. Because it's a much better conductor anything built with it produces much less heat. This allows them to get to these high frequencies.
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jeph_gag , April 12, 2011 11:13 PM

A transistor is used as an ON/OFF switch in digital application. But it's used as an amplifier in analog application.
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zzz_b , April 12, 2011 11:15 PM

The transistor can be in the active region, saturation region and cut-off region. So, it is an analog device, but in the saturation region is fully on, while in the cut-off region is off. These regions are used for the "digital" signal.
I guess most of you guys know only how to play Cryis. :-(
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f-gomes , April 13, 2011 12:04 AM

In IE9, comments don't work. The button does nothing. One has to use compatibility view in order to post a comment. Come on guys, it has been more than a month, now.
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scook9 , April 13, 2011 12:26 AM

zzz_bThe transistor can be in the active region, saturation region and cut-off region. So, it is an analog device, but in the saturation region is fully on, while in the cut-off region is off. These regions are used for the "digital" signal.I guess most of you guys know only how to play Cryis. :-(

We are not ALL electrical engineers afterall haha
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CerianK , April 13, 2011 12:53 AM

For high power analog applications, it is necessary to use a feedback temperature sensor on transistors to compensate for how the temperature of the device affects the active region. Hopefully, the graphene transistor will be scaled for these types of applications and be less susceptible to drift of the active region. Oh, and of course I would like to see them used in my next CPU, as well.
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milktea , April 13, 2011 1:07 AM

Graphene Transistor has zero bandgap, which is another form of a fancy resistor?
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TheCapulet , April 13, 2011 1:08 AM

scook9We are not ALL electrical engineers afterall haha

Then take 5 minutes to scan wikipedia before making a comment. Not only will you sound vastly more intelligent, you'll also manage to learn something today, as well as contributing something useful to the comment section.

And before this thought is bashed, I'm not saying wikipedia will make you, or make you sound more intelligent. The active pursuit of knowledge will.
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coconut , April 13, 2011 1:10 AM

Time to clear up some misconceptions here:

First, all transistors can be operated as analog devices or digital devices. Obviously, many are optimized/intended for use as one type or the other, but almost any transistor can be used in either mode.

Second, graphene is nowhere near a "superconductor" at normal temps. Not even close, and that's not the point of using graphene for anything. A true room-temperature superconductor will change the world in ways this transistor will not.

What is true, however, is that this is pretty a cool device.
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hajila , April 13, 2011 1:43 AM

Transistors are used for modulating voltage or current in a circuit based on an input. They can be thought of just like a faucet. Your input on the handle can make the water run slow or fast or not at all.
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cjl , April 13, 2011 4:44 AM

spiketheaardvarkone commentThe advantages of graphene do not come from transistor size but the fact that it's a superconductor at normal temps. Because it's a much better conductor anything built with it produces much less heat. This allows them to get to these high frequencies.

Graphene is not a superconductor. It would be great if it were, but it isn't (at least not anything remotely resembling normal temperatures).
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tehramen , April 13, 2011 5:51 AM

WyomingKnottSomeone enlighten me here. I thought that transistors were originally analog devices for many years. They had to be re-designed to be on-off devices. Am I wrong?

As far as I know, MOSFETs can be manipulated into electrical switches.
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bonedoctor , April 13, 2011 6:47 AM

Quote:
zzz_bThe transistor can be in the active region, saturation region and cut-off region. So, it is an analog device, but in the saturation region is fully on, while in the cut-off region is off. These regions are used for the "digital" signal.I guess most of you guys know only how to play Cryis. :-(

Yup we can play Crisis, but could a computer built with these transistors ;-)
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Flameout , April 13, 2011 7:29 AM

looks like chicken wire
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coconut , April 13, 2011 7:37 AM

Just to correct some severe misinformation from zzz_b:

Transistors have three modes of operation: Cutoff, linear (aka triode), and saturation (aka forward active).

Analog circuits generally keep transistors in the saturation region.

Digital circuits generally switch transistors between cutoff (off) and linear (on).

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