Transistor Museum Oral History Suran Page 5 GE Unijunction Transistors

EARLY TRANSISTOR HISTORY AT GE

Jerry Suran – The Story of the Unijunction Transistor

Oral History – Jerry Suran (Continued)

After that, with the flexibility we had with the tri-service contract, we simply pursued this (technology). We decided that this was an interesting device and we began to explore it and we began to have Saby’s group (my contact there was Arnie Lesk) to build these things purposefully. And I began to write papers on the so-called “double base diode”.

The first published paper I had, according to my records, was in March 1955 and was published in Electronics magazine, and shortly after that, in April 1955, I had one published in the IRE Transactions. These were theoretical and experimental papers, and they were (written) to describe the physics and electronic effect of this unijunction transistor. For example, the first paper in the IRE was entitled “Small Signal Wave Effects in the Double Base Diode”, and “Low Frequency Circuit Theory of the Double Base Diode”, a little bit later. The whole idea was to try to find out how this thing was working, so that it could be reproduced physically in a systematic way.

There must have been quite a bit of communication and feedback to the device group as you developed a better understanding of the physics of the device

Yes, that’s right. As we discovered more interesting features and as we thought we knew a little more about how these things worked, we had Arnie make them a little bit differently. Of course much later, I think around 1957, we switched from germanium to silicon.

Oral History – Jerry Suran (Continued)

Did General Electric ever sell any of the germanium unijunction transistors commercially, before switching to silicon? And what were the first applications?

As far as I know, yes. The unijunction transistor was a interesting device. We immediately recognized that this was a relaxation oscillator, and was the analog of the vacuum tube thyristor. We decided it could be used in any area where one needed a non-linear oscillator. If you wanted a saw-tooth, or you wanted a pulse, or you wanted to use this as a pulse width regenerative amplifier, or you wanted to build a multivibrator, this was good device. It would simplify the fact that you would normally have to use two transistors, and here you only had to use one. It had a built-in positive feedback effect.

Were there any surprises when moving from germanium to silicon with the unijunction?

The devices acted exactly the same. Silicon at that time had much higher surface recombination problems. The transistor gain-bandwidth initially in silicon was not as good as in germanium. Of course, the mobility of silicon was lower.

Go To Suran Oral History, Page 6

PAGE 5