Posted on 04/15/2005 2:06:56 PM PDT by LaserLock
A pair of physicists in the US has built the fastest ever transistor: one that can operate at a frequency of over 600 gigahertz. Developed by Walid Hafez and Milton Feng at the University of Illinois at Urbana-Champaign, the device is made from the semiconductors indium phosphide and indium gallium arsenide (Appl. Phys. Lett. 86 152101). The work demonstrates the feasibility of making transistors that can operate at frequencies of several terahertz, which could be used in ultrafast communications, high-speed computing, medical imaging and sensors.
The new device is a so-called bipolar transistor, which is very different from the more well-known field-effect transistor. In it, electrons are injected from the "emitter" terminal, travel towards the "base" and are then received by the "collector", an arrangement that allows the device to work faster than a field-effect transistor.
Hafez and Feng have previously built a high-frequency bipolar transistor, but this earlier work focused on reducing the time it takes electrons to pass through the device by minimizing the device's vertical thickness. Their new research further increases electron speeds through the device by slightly varying, or "grading", the composition of the semiconductor layers. This, say the researchers, lowers the band gap in selected areas of the transistor and makes it easier for electrons to travel across the device.
The two physicists have shown their transistor can operate at a frequency of 604 gigahertz, a new record. However, according to Hafez, what is more important is that they have developed a technology that could be used to build transistors operating in the terahertz range. "Projections from our earlier high-frequency devices indicated that in order to create a transistor with a cutoff frequency of 1 terahertz, the devices would have to operate above 10,000 degrees C," he says. "By introducing the grading into the layer structure of the device, we have been able to lower the potential operating temperature for a terahertz transistor to within an acceptable range."
Devices operating at terahertz frequencies (the far infrared) could be used in communications applications or as sensors to detect toxic gases. They could also be used for medical imaging, since the radiation is long enough to penetrate skin and image what lies underneath.
The researchers' next step is to show that their devices can be assembled into circuits.
A few million of them at .1 microns would make a gnarly processor.
I know you don't have a lot of tech on your science ping list, but this one has physics too, and looks like a big step. Could be worthy.
And a bi-polar, to boot. What's old is new again.
OK, it's a small thing but when I think transistor I'm thinking of a bipolar transistor. When I think FET then I'm thinking about a field effect transistor.
Of course I'm old enought to remember germanium transistors and the silicon versus germanium debate so maybe things have changes and I didn't notice.
600 GHz is very nice. Now I want a dual Pentium, quad core, 128 bit 600 GHz PC with a 100 GHz FSB. Something that will bring up the photos of the grandkids a little faster.
Now wait just a pico-second(or 1.66).
OK ... quick what's a SNn7400
Extra credit ... whats a 555
Thats SN7400 ... damn keyboard
Except it will never be produced in the US because someone somewhere will claim that this product causes hair loss and sue, bankrupting the manufacturer. :-P
Interesting, but it's not quite for my list. Try neverdem, who has a "health and science" list. I don't know if there's a computer ping list. Maybe ShadowAce, who has the "Firefox browser" list, and rdb3 has a Linux list. If in doubt, farmfriend keeps the list of ping lists.
The SN7400 is a quad dual input positive NAND gate, the 555 is a timer IC.
Any more, professor?
Is it just me, or does the way this works sound an awful lot like a synapse?
It sounds promising, but it ain't official until they test it on the Bonneville Salt Flats.
A 555 is a timer.
Extra credit ... what is the color is the cover of the old Signetics TTL book
The new device is a so-called bipolar transistor, which is very different from the more well-known field-effect transistor. In it, electrons are injected from the "emitter" terminal, travel towards the "base" and are then received by the "collector", an arrangement that allows the device to work faster than a field-effect transistor.
I was building these at Signetics in 1984.
Are you there, HAL?
BTW ... I still have mine
one that can operate at a frequency of over 600 gigahertz.
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Big deal . . . my cheeks vibrate at 601 gigahertz each and every time I traf !!! ;-))
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