On a cold December day 1947, Physicists Walter Brattain, William Shockley and John Bardeen crammed a couple of electrodes into a piece of germanium. They didn’t know it then but what they invented would change the world forever.
The transistor is arguably the most important invention of the 20th century. The first one might not have been pretty but with it came the dawn of a new era ‘The Information Age’.
Just like cells are the building blocks of life, transistors are the building blocks of our modern day electronics. Mobile phones, tablets, PCs, laptops, PlayStation, wrist watch wouldn’t exist as we know them without transistors. Now what is a Transistor?
The simple answer is, it’s a switch, just like a light switch it turns on and off but unlike a light switch it has no mechanical moving parts. This is possible through the magic of Physics and Chemistry.
It can switch up to 100 billion times in one second. It would take you about 2000 years to flick a switch on and off that many times. Amazing isn’t it?
Transistors work something like a water fosset. Not only do they start and stop the flow of a current but they also control the amount of current. They can switch and amplify electrical signals meaning that they can move electricity through a circuit board with extreme precision. That’s why we have such powerful devices in such small packages.
Today’s Transistors are tiny, I mean really really tiny. Think about the head of a pin-pretty small right, Well you can fit 100 Million transistors on one. If you expand each transistor present in a smart phone to the size of an apple then that smartphone would have to be larger than the entire earth.
One of the first application of transistor was to make smaller more portable radios. Transistor made it possible to amplify sound in a smaller package so people were able to take their music out into the world with them. Now it is billions of transistors that work together to run the programs like to watch a video but the transistor radio had only four transistors.
How do transistors move electricity around?
There are different types of transistors. A very common one is the Bipolar Junction Transistor or BJT. And it usually looks like this:
It has three pins: Base (b), collector (c) and emitter (e). And it comes in two versions: NPN and PNP.
Transistors are made from Silicon- a chemical element found all over the earth. Silicon is a ‘Semiconductor’ meaning it conduct electricity better than an insulator like a plastic but not quite well as metals like copper. However you can make silicon— more of a conductor by using a process called Doping. It’s when you inject a foreign substance in order to improve or inhibit performance.
Silicon when doped with an element from group 5 like Phosphorus results in an N-type and if we dope silicon with an element from group 3 of the periodic table like Boron, P-type transistor is made.
By doping silicon with other elements we know how two materials that we can put together to make transistors.
Field Effect Transistors (FETs):
FETs are electrical switches that are controlled by an applied electric field. These kinds of transistors have three major parts: Source, Gate and Drain. Electric current flows through the transistor from the source to the drain and the gate controls whether the current can flow or not and is insulated by an oxide layer. Recall the water fosset terminology from earlier – the handle of the fosset is like a Gate and the application of voltage controls it. FETs can switch on and off extremely fast without the movement of mechanical parts.
One of the most recent transistor design is the ‘FIN FET’ i.e. Fin shaped field effect transistor. This kind of transistor place the source and drain into a standing fin and the gate electrode surrounds the channel for even more precise performance. The most recent Fin FET transistors are only 14nm wide, that a few dozen atoms across.
When a Transistor turns ON, it’s ONE in a computer language of Binary, when it’s OFF it’s a ZERO.
Billions and Billions of zeros and ones put together make up the programs and functions of our electronic devices. To compute these complex tasks, a group of transistors work together on an Integrated circuit better known as the Computer Chip. Microprocessors are among the most advanced ICs and they control everything from computers to smartphones to digital microwave oven.
The first IC was a little messy but it changed the way transistors were put together. Soon engineers were able to put more and more transistors together to compute as a unit. Originally there were few Transistors on an IC. A 64GB thumb drive today has over a 100 billion circuit elements.
A few years after those first computer chips were created engineer and co-founder of Intel Gordon Moore predicted that the number of transistors on a chip would double roughly every two years. This phenomena turned out to be true and Moore’s Law has held to this day. As a result the cost of transistor continues to go down exponentially.
What if we reach the limit of Moore’s law in our life time? Even today transistors are so very small. Some speculate that one day scientists will be able to store memory in a single atom. Think about how small your smartphone will be then.
In the almost 70 years since the invention of first transistors, our world has completely changed. This teeny slab of silicon has influenced almost every modern invention, industry, and home.
Thanks to Google and YouTube