Transistors replaced vacuum tubes, computers went from the size of the entire rooms to merely the corner of a room
Electronics keep getting smaller, and it’s all thanks to electric switches called Transistors. When these little devices replaced vacuum tubes, computers went from the size of the entire rooms to merely the corner of a room. In the 60-odd years since, transistors have kept shrinking, scaling down, and powering up our electronics with them. But many think we are hitting a choke point…What if we can’t make anything smaller? A transistor has three terminals; a source, a drain, and a gate. Current flows from the source and if the gate allows the electrons to pass out the drain. You know how computer codes are 1’s and 0’s at its most fundamental level? This is where that physically happens.
Current flowing through an open gate represents a 1, a closed gate and no current represents a 0. Pack thousands of these transistors together and they can do calculations and act as a computer’s brain or CPU. Early computers had thousands of transistors, but one way to build a better brain is to squeeze more transistors onto a chip, and today’s chip could have billions and that means scaling all the parts of a transistor down. Not only do smaller transistors allow for a higher density, but it also means they can switch from on to off faster, so small is good.
Right now, commercially available chips typically have transistors with gates about 14 to 20-nanometer across depending on the chip. The problem is, as gates get thinner, quantum mechanics (the physics that governs tiny parts of atoms) start to come into play. For example, if the gates are too thin then they won’t be able to stop the electrons because the electrons will tunnel through the gate. Not in the literal sense, they don’t bore through the gate like an escaped convict. They tunnel in the quirky quantum sense, where essentially electrons disappear on one side of the gate and reappear on the other. If the gate is supposed to be close to current, means a 0, and it isn’t, this tunnelling can be a big problem.
Researchers predict that the lower limit for silicon gate is 5-nanometer, and by 2021, it won’t be economically efficient to keep shrinking transistors. So, where do we go when the laws of physics stop the march of technological progress? Well, there are indeed other ways of improving the performance. Machine learning could help develop more efficient algorithms to use with current transistors. Or, we could switch to light based computers with optical gates. That could actually boost performance 20-fold, though the hardware is a bit larger. Or, we could also stop using silicon altogether. Researchers have managed to make a transistor out of Molybdenum disulfide with a carbon nanotube gate that is just 1-nanometer across. It gets around electron tunnelling because electrons don’t flow as fast through the Molybdenum disulfide as they do through silicon.
Mass production would probably be expensive; it was hard enough to make the proof of concept. The point is, progress can happen even if we can’t shrink these things. Keep in mind that when the transistors were first used in a computer they were 20 times more expensive than vacuum tubes. Even though transistors were much costlier, computer scientists knew they had more of an upside in the long run and look where that led us. Now we are watching cat videos on our phone while avoiding eye contact during your commute to work. Fun fact is that the first point-contact transistor was invented in 1947, and that was made from strips of gold foil, a plastic triangle and a germanium crystal that is pushed down on. We sure have come a long way.