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Material World
Object

Transistor

The most manufactured object in history by an enormous margin, and the reason silicon is refined further than any other material.

A transistor switches or amplifies a current using a semiconductor in which conduction can be controlled by a third terminal. It replaced the vacuum tube because it is smaller, needs no heater, does not burn out, and can be made by the million on one piece of crystal.

Its material requirement is extreme and specific. The doping that makes a semiconductor work is measured in parts per billion, so anything else present at that level ruins it — which is why semiconductor silicon is purified to around eleven nines and grown as a single crystal with essentially no grain boundaries.

History

Demonstrated at Bell Labs in December 1947 by Bardeen and Brattain as a point-contact device on germanium; Shockley's junction transistor followed and is the practical one. The 1956 Nobel Prize went to all three.

Germanium came first and silicon displaced it, on the oxide rather than on any electrical property: silicon dioxide is stable, adherent and insulating, which lets the surface be masked during doping and then left in place. Germanium oxide dissolves in water. The planar process built on that, and integrated circuits followed.

MOSFET production is now estimated in the sextillions, which makes it the most-manufactured artefact of any kind by several orders of magnitude.

Cultural significance

It is the component every other modern technology is assembled from, and it is invisible: nobody buys one, sees one, or can point at one. A material's most consequential application can be something the public has no relationship with at all.

The transistor radio of the 1950s is the exception, and the one place the word entered ordinary language — it was the first consumer product whose selling point was the component inside it.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is made of

  • Silicon — element · the substrate, purified to around eleven nines — a purity nothing else is produced at in bulk
  • Germanium — element · the first one, and displaced by silicon on the oxide rather than on any electrical property

is made using

  • ABS — material · not the device but the package and the board hardware around it — the plastics are most of what a reader actually handles
  • Gallium nitride — compound · as the high-electron-mobility transistor that has taken most of the high-power radio-frequency market — 5G base stations, radar and satellite transmitters

is associated with

is used in

  • Electronics manufacture — industry · the component every other modern technology is assembled from, and one nobody ever sees

Sources

  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Material World
    Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Transistor back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Transistor → is made of (the substrate, purified to around eleven nines — a purity nothing else is produced at in bulk) → Silicon → is produced by (carbothermic reduction of silica with coke in a submerged arc furnace, which is smelting in the strict sense even though no ore is involved) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Transistor → is made using (not the device but the package and the board hardware around it — the plastics are most of what a reader actually handles) → ABS → is produced by (styrene and acrylonitrile polymerised in the presence of polybutadiene rubber, so the rubber phase is grafted in rather than blended) → Polymerisation → takes as input (as vinyl chloride, which is why more than half of PVC's weight is salt rather than oil) → Chlorine → is produced by (at the anode) → Chlor-alkali electrolysis → takes as input (as brine; the salt is the feedstock for both products at once) → Halite
  • Transistor → is made using (as the high-electron-mobility transistor that has taken most of the high-power radio-frequency market — 5G base stations, radar and satellite transmitters) → Gallium nitride → is sourced from (produced overwhelmingly in China, which introduced export controls in 2023 — a vulnerability that comes from the metal being somebody else's by-product rather than from any scarcity) → Gallium → is sourced from (as a by-product of the Bayer process) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (an early-crystallising constituent of basaltic magma) → Olivine
  • Transistor → is made of (the first one, and displaced by silicon on the oxide rather than on any electrical property) → Germanium → is sourced from (from the flue dusts of zinc smelting, and from coal ash — dispersed at parts per million everywhere and concentrated nowhere) → Zinc → is produced by (as the oxide, which is then reduced — roasting is the step that makes zinc sulfide smeltable) → Roasting → takes as input (a copper sulfide; roasting drives off the sulfur that would otherwise prevent reduction) → Chalcopyrite
  • Transistor → is made of (the substrate, purified to around eleven nines — a purity nothing else is produced at in bulk) → Silicon → is sourced from (reduced with carbon in an electric arc furnace) → Quartz
  • Transistor → is made using (not the device but the package and the board hardware around it — the plastics are most of what a reader actually handles) → ABS → is produced by (styrene and acrylonitrile polymerised in the presence of polybutadiene rubber, so the rubber phase is grafted in rather than blended) → Polymerisation → takes as input (as tetrafluoroethylene, which is where a substantial share of industrial fluorine chemistry ends up) → Fluorine → is produced by (electrolysis of potassium bifluoride, which is molten and conducts — there is no chemical oxidant strong enough to displace fluorine from a compound, so electricity is the only route and always has been) → Molten salt electrolysis → takes as input (after concentration, as one of the two routes to lithium chloride) → Lepidolite

These are the most distinct paths back. Transistor can be traced through others besides.

Downstream — what it becomes