IRA FLATOW: This is Science Friday. I’m Ira Flatow.

75 years ago this month, December 23, saw the creation and unveiling of what some call the greatest invention of the 20th century, the transistor, unveiled at Bell Labs, the research arm of Ma Bell. It was a clunky looking thing, with two gold contacts on a plastic wedge pressed against a crystal of germanium. But that early transistor had a magical property. A voltage in one part of the device could control the electrons in another part of the transistor.

It could be a switch or an amplifier. It was the first semiconductor. And that device, and the ones that followed and improved on, would become an essential part of modern life. Your cell phone today likely has billions– with a B– billions of transistors in it, and soon to have trillions inside.

Here to help put that anniversary in context is Michael Riordan. He’s a physicist, science historian, author of several books, including Crystal Fire: The Invention of the Transistor and the Birth of the Information Age, co-authored with Lillian Hoddeson.

Welcome back to Science Friday, Michael. It’s been a few years.

MICHAEL RIORDAN: Yes, it’s been about 25 years, if remember correctly.

IRA FLATOW: Yeah, we celebrated the 50th anniversary. Now we’re back with 75. Well, take us back 75 years. They used to say necessity is the mother of invention. Why was Bell Labs, the phone company, interested in creating a transistor at this time?

MICHAEL RIORDAN: Well, led by Mervin Kelly, who was then the vice president of Bell Labs, they could see that, after World War II, there would be an enormous need for telephones. In fact, I think he projected that, if they did nothing else, using their old electromechanical switches, that they would need to hire all the women in the United States to serve as operators.

IRA FLATOW: No kidding.

MICHAEL RIORDAN: So they were looking for something to get beyond these switches and vacuum tubes, and thought that the solution would occur in solid state physics. So he set up a solid state physics group at Bell Labs just after World War II, headed by the theoretical physicist William Shockley. And Shockley gathered not just physicists but chemists and engineers– electrical engineers in particular– into a multidisciplinary group to study solid state physics and how it might improve communications.

And out of that group, two of them, physicists John Bardeen and Walter Brattain, came up with the first transistor, the point-contact transistor, on December 23, 1947.

IRA FLATOW: Now, the interesting part of that story, if I recall, is that Brattain and Bardeen created a transistor that Shockley was not looking for, right, a different transistor than he had in mind?

MICHAEL RIORDAN: Yeah. Shockley was trying to come up with what is called a field-effect transistor. And in fact, in modern life, all the billions of transistors on at least my microchips in this computer, are field-effect transistors. But there was a problem with field-effect transistors. There would be a layer of electrons on the surface that would prevent the field from getting inside and influencing what was happening with the electrons and holes. Holes are like the absence of electrons in a crystal.

And Bardeen and Brattain came up with a way to get beyond that by putting two sharp points close together on a germanium surface– not silicon– they were working with germanium, which was a lot easier to work with– and injected holes into the innards of that slab, thereby influencing what was going on– the currents that were flowing beneath.

IRA FLATOW: Was there a breakthrough, an aha moment, that made this all possible?

MICHAEL RIORDAN: Well, I think it was a series of small breakthroughs happening all through the month of December, one after another. I can’t really point to one great breakthrough there. It was just the combination of Bardeen’s theoretical insight and Brattain’s experimental dexterity that made it possible. Bardeen realized that there were these objects called holes. It was not, by no means, common knowledge in those days, in 1947, but he was the one who thought of minority carrier injection, that holes were being injected into the innards, that made it all possible.

IRA FLATOW: Now, if you look at patents, there are claims around transistor-like devices even before then. So what’s the catch?

MICHAEL RIORDAN: Well, there was a patent by Julius Lilienfeld going back I think to 1930. He was not a Bell Labs person. He was a physicist. He never, as far as I can tell or historians can tell, he never made one of these devices. But it really was the field-effect transistor. So Shockley could not have claimed a patent on the field-effect transistor.

And let me add that he felt he was being scooped by his own employees– or members of his group I should say. And so, starting on about New Year’s Eve, at that party that same year, he went away and started working in his hotel room to try to come up with an alternative device that he could patent and claim as his own. And that led to the junction transistor, which was a lot more easily manufactured device.

IRA FLATOW: Right. And in fact, Shockley would go on to fame on his own, would he not?

MICHAEL RIORDAN: Oh, yeah. His coworkers said that Shockley could virtually see what was going on with electrons inside matter. He really deserved his part of the credit. He just had difficulty sharing it with others.

IRA FLATOW: Yeah. In fact, there’s a very famous picture on the anniversary– a very famous picture of the three of them gathered around a transistor and a microscope, if I remember correctly. And it’s Shockley who’s sitting there as if he’s working on the transistor. But he never really did any of that, did he?

MICHAEL RIORDAN: No. He was terrible at the lab bench. And in that picture, I can recall, Brattain has a grimace on his face, as if to say, what is this guy, this theorist, William Shockley, doing looking in my microscope?

IRA FLATOW: Yeah. And before there were transistors, we all back in the day knew there were vacuum tubes, right? How was this different? What could it do that a vacuum tube could not?

MICHAEL RIORDAN: Well, it was a lot smaller and it didn’t generate heat. I mean, vacuum tubes were pretty sophisticated devices by the end of the 1940s. I remember that it took a while before transistors were able to surpass them in high fidelity recording, for example. But the fact that they generated heat, that they burned out, that they took up so much space, that they were difficult to manufacture, I think ruled them out as miniaturization became important both commercially and to the US military.

IRA FLATOW: And of course, then, that led to the famous transistor radio of the ’50s, right?

MICHAEL RIORDAN: Yeah.

IRA FLATOW: And the Japanese were very much involved in the early transistor radios. That was because they were prohibited from producing– after World War II– from producing any defense capabilities. And so they sunk it into commercial stuff like transistor radios.

MICHAEL RIORDAN: Yeah. The beginnings of Sony have to do with the first Japanese transistor radio, which came in in the mid– I think about 1956– just after the very first transistor radio produced by Texas Instruments, the TR-1.

IRA FLATOW: And what’s also interesting about that and what Bell Labs did is Bell Labs invented it, but they did not keep the intellectual property secret. They realized how big an invention this was and were willing to let other people, other countries, share in that knowledge, right?

MICHAEL RIORDAN: Yeah. They realized that, even with all the intellectual capital that they had at Bell Labs, that important discoveries were going to occur elsewhere. And so they licensed it pretty liberally up until 1956, when there was a consent decree that said they had to make the original transistor patents available free of charge. But they were on that road anyway. I didn’t think that made much difference. They were interested in using the transistor to improve communications.

And there were many other applications that they were not interested in. For example, hearing aids. Before the transistor, people had to carry a big package on their belt with vacuum tubes and batteries, and then lines going up into their ears, to have hearing aids. I’ve actually got hearing aids right now. They’re totally self-contained. They’ve got a microchip in them that– I don’t know how many billions of transistors are on them.

IRA FLATOW: You mentioned that that first transistor was made out of germanium. Why was then a switch made to silicon?

MICHAEL RIORDAN: The driving force for silicon was mainly the military. Germanium, although it was really easy to work with, suffered from the fact that its performance varied with temperature. You got up to about 75 degrees centigrade, they stopped working altogether. And the military could not tolerate that. So they were pushing hard in the mid ’50s for silicon transistors. I mean, they were willing to pay $100 per transistor.

IRA FLATOW: We’re also talking about the age of Sputnik and rocket launches, and the military wanted to shrink things down– needed tiny little devices.

MICHAEL RIORDAN: Yeah. Oh, definitely. I mean, the Russians I think used vacuum tubes in the first few Sputniks. But they had the enormous thrust capacity of their rockets. The United States– and I remember the first Vanguard collapsing on the launch pad. The United States was way behind in thrust capacity in the mid ’50s, so it really needed to lighten the load. And transistors allowed them to do that.

IRA FLATOW: Let’s talk about what’s actually going on in the device itself. You mentioned it briefly, but let’s talk about there being different kinds of transistors. The first device was called, as you mentioned, a point-contact transistor. But the ones that are so present today are largely field-effect transistors. What’s the difference?

MICHAEL RIORDAN: Well, in the field-effect transistor, which was the original conception of Lilienfeld and Shockley, you have a metal contact on the surface. And below that you have silicon dioxide. That’s the oxide layer on silicon. And below that you have silicon. And the actual electrical activity takes place inside the silicon. But you need to bring– if you’re going to change the behavior underneath that silicon dioxide insulating layer, you’ve got to bring in a field on that metal lead on top.

And that really very fundamentally– very simply, I should say– is how the field-effect transistor works. There’s charge coming from one side and flowing to the other side. It can be electrons. It can be holes. And you influence that left-to-right flow by changing the field on the metal above the silicon dioxide layer.

IRA FLATOW: And that first device was called a point-contact transistor. Because instead of bringing a wire, let’s say, a contact with an electrical field, close to it and having the field affect the surface, you actually had to touch it, right, with the wire?

MICHAEL RIORDAN: Yeah, you had that wire sticking into a germanium surface. I don’t think there was ever any point-contact silicon transistors.

IRA FLATOW: This is Science Friday, from WNYC Studios, talking with Michael Riordan, physicist and science historian, about the invention of the transistor 75 years ago.

And so the three of them shared a Nobel Prize. But their relationship was never repaired, I don’t think, over the years because of Shockley trying not to give anybody else credit.

MICHAEL RIORDAN: Well, there was a lot of grief in that group. And I think Bardeen eventually left and took up a professorship at the University of Illinois because he just couldn’t continue to work for Shockley. That must have been– but I think, by the time they all shared the Nobel Prize, they began coming together again.

When you’re leading up to the Nobel Prize, there is a lot of grief or, you can say anxiety, that gee, maybe I’m not going to win it.

IRA FLATOW: Right.

MICHAEL RIORDAN: And that creates barriers. But after they were– and I think justifiably– when they all shared the 1956 Nobel Prize in Physics, I think that rivalry at least dissipated.

IRA FLATOW: Do you think they– anyone really understood at that time how significant that invention would be, how ubiquitous it would be, how important it would be, to creating the world we have today?

MICHAEL RIORDAN: I don’t think anybody did. Let me just give you some numbers, if I may. In December 1947, there was exactly one transistor in the entire world. There are now something like 20 sextillion. Now, what’s that? Well, that’s 20 billion trillion transistors in the world. And that’s about 3 million transistors per square foot of land surface all over the entire world– 3 million transistors per square foot.

Now, there are 114 billion transistors in the M1 chip in my computer that allows me to talk to you right now.

IRA FLATOW: And they’re shrinking all the time, aren’t they? They’re putting more and more transistors on chips all the time.

MICHAEL RIORDAN: And that’s a good point. Because how small you can make the transistor determines how many transistors you can put on a single chip and how powerful it is. I think the leader in that field is Taiwan Semiconductor. They’re trying to get down to 3 nanometers per the size of each transistor. And I just read that they’re planning to spend $14 billion to try to do so in Arizona.

IRA FLATOW: Yeah. They’re moving some production. Yeah.

MICHAEL RIORDAN: As opposed to the Mainland Chinese can get down to 14 nanometers. The Russians can get down to about 28 nanometers. And that tells you the sophistication of the electronics that they can produce.

IRA FLATOW: And even though the three shared a Nobel Prize, they didn’t make much money off of it, did they?

MICHAEL RIORDAN: No. I think they got paid $1 by Bell Labs for the rights to the transistor.

IRA FLATOW: Wow. Well, that’s a good place to wrap up, to see how much it was worth to them compared to how much it is worth to the world. Thank you, Michael, for your work and for taking time to be with us today.

MICHAEL RIORDAN: Thank you very much. And I hope everybody will read about this in Crystal Fire, which is still in print after 25 years.

IRA FLATOW: Michael Riordan is a physicist, science historian, and author of several books, including the aforementioned Crystal Fire: The Invention of the Transistor and the Birth of the Information Age, co-authored with Lillian Hoddeson.

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