UIUC Researchers Create Light Emitting Transistor

thesilverbail writes "Researchers at the University of Illinois have demonstrated light emission from the base layer of a Bipolar Transistor. This discovery could be the beginning of an era in which photons are directed around a chip in much the same fashion as electrons have been maneuvered on conventional chips. It's reminiscent of the exciting days of the Miracle month November, 1947, when the transistor was first invented."

Comments

This doesn't seem to mean much

[Tau Zero]

First, there's no real magic here; the news release says that the transistor is "made from indium gallium phosphide and gallium arsenide."

What this means is that someone has taken the same materials which emit light as part of a single-junction device (a diode) and have also made them do so as part of a bi-junction device. While this looks like it might be a good way to integrate light emission with the control circuitry, it's not going to do anything to make them easier to integrate into large devices (silicon works for this because its oxide, SiO2, is a pretty good insulator while gallium doesn't do anything so convenient).

I will admit that it's clever, and someone may find some unobvious way of turning it into a useful device (massively parallel optical interconnects?), but there's just no way that this is going to be slapped onto the next Intel or AMD die. It especially will not replace aluminum or copper interconnects between parts of one processor.

This isn't what you think

[Cyclone66]

It's an extension of the idea of the Light emitting Diode but it doesn't mean we'll have optical computers any time soon. The transistor still runs on current, it only outputs light! That means it can not drive another LET which means fully optical based devices aren't possible.

What this DOES mean however, is smaller devices in the realm of electronic/optical interaction. The basic functionality of this transistor is similar to a small combination of transistors and diodes except that this does it in one device. The device is rather large but it'll probably shrink rather quickly as it's still in the early stages of development.

Re:This isn't what you think

[grayrest]

Actually, it outputs both current and light. The light just happens to be a byproduct of the electron-hole recombination in the material. I do believe that the two outputs will be either the same or opposite depending on transistor type (pnp or npn) so you really don't get anything out of the transistor that you weren't getting already, you just get it in a different format. I'm sure, however, that someone more creative than myself will find some cool use for this.

You're extremely unlikely to see this type of technology in a microprocessor, at least in it's current BJT form. Most if not all microprocessors use MOS-type transistors because they're much easier to fabricate. BJTs are usually used in electronic amplifiers, though either can be used in either scenario depending on how the circuit is set up.

Re:End of interchip communincation problem era!

[stj]

You are right, however you are wrong ;-) Well, speed of light is not the only problem. One of the major complications in electrical wiring is that at high frequencies even a couple inches turns into long distance telecommunications and you have to construct actual transmission lines with matching impedances. Using optics eliminates this problem. Now if you talk about speed of light, at the distances of inches that's far less relevant than you think. Typically much more problem is with the transmission rate and synchronization than actual propagation delay.

Inside single chip the situation is different, because the maximum delay pretty much determines clock rate.