Roughly 13 sextillion MOSFETs were made between 1960 and 2018
One kind of switch dominates the modern world so thoroughly that it makes up at least 99.9 percent of all transistors ever built. An estimated 13 sextillion of these MOSFETs were manufactured in under six decades. They, and their semiconductor cousins, quietly took over the jobs once done by glowing vacuum tubes.
Semiconductors sit between conductors and insulators, and their charm is how easily that in-between state can be tuned. Sprinkle in a trace of an impurity such as phosphorus or boron, a process called doping, and the supply of mobile electrons or of holes, the gaps electrons leave behind, rises sharply. Material rich in holes is p-type; material rich in electrons is n-type. Light, heat, electric and magnetic fields, even bending the crystal can shift conductivity too, which makes semiconductors natural sensors.
Join p-type and n-type material and you get a diode. Where they meet, a thin zone empty of free carriers forms; push voltage one way and the zone shrinks so current flows freely, reverse it and only a trickle gets through. Shine light on the junction and it makes fresh carriers, the principle behind photodiodes, while some compound materials run the process backwards to emit light in LEDs and laser diodes. Stack two junctions and you have a bipolar transistor, where a small current into the thin middle layer controls a much larger one across the device.
The MOSFET works differently, using an electric field from an insulated gate to open or close a channel between two terminals. Despite the metal in its name, modern gates are usually polysilicon. Billions are produced daily, and annual shipments of all semiconductor devices were expected to pass one trillion for the first time in 2018.
Silicon rules because it is cheap, relatively easy to process and works over a useful temperature range, and it is grown into crystals wide enough for 300 millimetre wafers. Germanium, an early favourite, proved too heat-sensitive and now mostly appears alloyed with silicon for very fast chips. Gallium nitride, with a band gap over three times wider, is gaining ground in power electronics and LEDs.
Source: Semiconductor device
