Without a doubt, one of the greatest inventions of the 20th century was the transistor which appeared in 1947. Of course, prior to this, there was a lot of work that went into making it over many years and many people like Thomas Edison, John Fleming and Julius Lilienfeld played a role in their creation and more importantly, that of the transistor’s predecessor, the vacuum tube aka, the thermionic valve. The vacuum tube came about in 1904 and it basically uses a heated cathode to get electrons moving towards a positively charged plate elsewhere in the tube. They’re called vacuum tubes because there was no air in them which helped electrons move more efficiently. These tubes were used to create early computers like the Atansoff-Berry computer which became functional in 1942 and led to the development of other computers like Colossus which was used during World War II for code breaking. Of course these vacuum tube computers were very large, inefficient and produced a lot of heat. Certainly a far cry from the personal computer.
While certain types of vacuum tubes could amplify signals, they were not ideal due to their inefficient nature using too much power. So, in the 1930s, Mervin Kelly of Bell Lab’s at AT&T realized that for the continued growth of the phone business, technology needed to improve. Years of development ensued by his team consisting of William Shockley, John Bardeen and Walter Brattain. Bardeen and Brattain made some interesting discoveries about the behavior of electrons and without Shockley they created the first point-contact transistor out of gold foil, plastic and germanium. Here’s a description of why such a shoddy-looking thing actually worked. Feeling left out, Shockley attempted to one-up them by making the sandwich transistor which was more usable and easier to make. This breakthrough led to the first silicon transistor developed by Texas Instruments several years later and ultimately the mass production, miniaturization and ultimately greater efficiency and overall advancement of modern electronics.
Transistors basically do the same kinds of jobs that vacuum tubes did, basically amplifying and/or switching a signal, but there are many variations on this device which have arisen since the first transistor including integrated circuits which actually contain many, MANY transistors. Some of the available transistors include: N-P-N and P-N-P transistors, junction transistors, and heterojunction bipolar transistors, among many others. You can read about how some of those work here. Even the most basic transistor is an improvement over the best vacuum tube.
While originally larger and somewhat more expensive, today, transistors are readily available and extremely cheap. If you need transistors, you can get 100 transistors (15 types) for just over $20 with the Elenco TRAK-100 and you can get a transistor tester as well. Velleman also makes transistors and you can get 100 transistors for less than $20 with Velleman K/Trans1 100 set. You can also see a huge section of all types of transistors made by NTE Electronics including regular transistors and integrated circuits. Today, high quality transistors are well made and affordable making them accessible to anyone who’s clever enough to make things with them.
Originally a groundbreaking piece of technology, transistors have become commonplace and are often overlooked, which is good in a sense because that makes them affordable. Thanks to improvements in materials and technology, transistors have continued to grow smaller and smaller and Moore’s law predicted that the number of transistors in an IC could double about every two years. This of course means that there is an eventual end for making smaller transistors, presently we’re at 5nm and 2021 predicts we’ll have transistors that are 3nm. To put things in perspective, a nanometer is 1/1000000000 of a meter, or 1/1000 of a micron. Normal bacteria can be anywhere from 1-10 microns. This chart makes the size easier to comprehend. That’s all pretty small, and it’s getting harder to make things smaller, so, some believe Moore’s law will be reached by 2025, and after that point smaller transistors cannot be made while others think we’re pretty much there already. In either case, Intel is slowing down on this miniaturization and focusing on developing new materials and methods to compensate once Moore’s law is reached.
Transistors will likely be used for some time, especially as new designs are employed and perhaps they will be used in conjunction with new technologies. Transistors appear to be here to stay, even if they will be undergoing some major changes in the coming years. It will definitely be exciting to see what the future holds with the development of nanomaterials and quantum computing and how this will affect transistors as we know them.