What do you think is the greatest invention of all time? Is it airplanes or computers or cell towers or maybe the internet?
Well, arguably, its something way smaller, nanometers to be exact. A transistor.
So, what is a transistor? Invented by John Bardeen, Walter Brattain and William Shockley in 1947 at Bell Laboratories, a transistor is a semiconducting device used to manipulate electric signals and power.
Now, that didn’t sound so interesting. So let me put it this way, without transistors, you wouldn’t be able to attend this online class, or play computer games or watch Netflix, frankly without transistors electronic devices won’t exist. This single invention gave rise to our smart phone equipped generation.
Before transistors, we used to have something called vacuum tubes, they were way bigger than transistors. The first computer “ENIAC” used 18,000 vacuum tubes to perform calculations, but it weighed 30 tons and took an entire room, and it was incredibly power hungry and the tubes regularly burnt out because the cathodes needed heat to work. Today, its computing power can be contained on a silicon chip no larger than a grain of sand, all thanks to the transistor.
The average smart phone has around 2 billion transistors but let’s see how they work on a singular level.
Most transistors are made of silicon, an amazing semiconductor. Silicon readily makes 4 covalent bonds with its neighboring silicon atoms, now if we introduce impurities like boron and phosphorus, we can change how it conducts the current. Adding phosphorus creates and extra negative charge which can roam around is known as N-type conductor and boron creates a creates a mobile positive charge known as a hole, known as P-type. When we arrange these two structures in a certain way and attach terminals to each end we create the most prevalent transistor, the NPN transistor. Free electrons from the n-type will migrate over to p-type to fill in the gap. This creates a boundary layer called the depletion layer which prevents more electrons from passing on but when a positive charge is applied to the base, it negates the depletion layer and allows current to flow, completing the circuit.
These transistors are then used in multiple logic gates which to modify the binary codes used in computers.
Modern computers can perform millions of calculations each second and they are still getting faster. Moore’s law states that the density of transistors on integrated circuits will double every two years and that trend has held until very recently, now it’s starting to slow down, due to multiple reasons. One of them being quantum tunneling, the thing is, the size of the transistors has gotten so small that the barriers between the sections of one are so thin that they allow electrons to pass through.
The age of transistors will eventually come to a halt so, will we have to decentralize computers to the internet of things or will we have to harness quantum mechanics to counter the load? Either way, One thing is for sure, the computer industry will have to redefine itself in the near future.