Element · Ge

Germanium

The semiconductor the transistor was invented in, then displaced by silicon.

The first transistor, demonstrated in 1947, was germanium. Silicon replaced it within two decades for a reason that has little to do with the semiconductor itself: silicon's oxide is an excellent, stable insulator that grows directly on the surface, and germanium's is water-soluble. The ability to grow a good insulator in place is what makes integrated circuits manufacturable.

Germanium remains in use where its properties are specifically wanted — infrared optics, fibre-optic glass, and as a strained layer in high-speed silicon devices.

Uses

Germanium was the first transistor material and was displaced by silicon, but it did not disappear. Its transparency to infrared makes it the standard lens and window material for thermal imaging — night vision optics are usually germanium.

It is also used in fibre-optic cable, where germanium dioxide raises the refractive index of the core glass, and in high-efficiency multi-junction solar cells for spacecraft. Silicon-germanium alloys give faster transistors than silicon alone in high-frequency circuits.

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 used as

Lighting — application · in infrared optics rather than visible emission

is an alternative to

Silicon — element · silicon displaced germanium in semiconductors within two decades — not for better semiconductor properties but because its oxide is a stable, insulating, easily grown film and germanium's is not

is sourced from

Zinc — element · from the flue dusts of zinc smelting, and from coal ash — dispersed at parts per million everywhere and concentrated nowhere

is produced by

Solvent extraction and electrowinning — process · leached from zinc smelting residues and coal fly ash and separated by solvent extraction — dispersed everywhere at parts per million and concentrated nowhere

is found in

Optical fibre — material · the dopant that raises the core's refractive index above the cladding's, which is the entire mechanism — and a substantial share of what germanium is used for

is used in

Transistor — object · the first one, and displaced by silicon on the oxide rather than on any electrical property

is associated with

The semiconductor era — event · first, and displaced — its oxide dissolves in water, which the planar process cannot tolerate

Sources

Material World
Our own writing
Wikidata
Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
PubChem
US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
NIST — National Institute of Standards and Technology
United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Germanium 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

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
Germanium → is produced by (leached from zinc smelting residues and coal fly ash and separated by solvent extraction — dispersed everywhere at parts per million and concentrated nowhere) → Solvent extraction and electrowinning → takes as input (in the low-grade and oxidised ores that flotation cannot economically treat, with bacteria oxidising the sulfide into a form the acid can attack) → Chalcopyrite
Germanium → is produced by (leached from zinc smelting residues and coal fly ash and separated by solvent extraction — dispersed everywhere at parts per million and concentrated nowhere) → Solvent extraction and electrowinning → takes as input (a carbonate dissolves straight into acid, which is why an oxidised orebody goes to a leach pad and the sulfide beneath it goes to a smelter) → Malachite
Germanium → is produced by (leached from zinc smelting residues and coal fly ash and separated by solvent extraction — dispersed everywhere at parts per million and concentrated nowhere) → Solvent extraction and electrowinning → takes as input (leached with acid or alkali depending on the host rock, which is what decides the flowsheet of a uranium mill) → Uraninite
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 (roasted for its sulfur as much as for its iron) → Pyrite
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 (roasted to the oxide, the sulfur going to an acid plant rather than the air) → Galena

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

Downstream — what it becomes

Germanium → is used in (the first one, and displaced by silicon on the oxide rather than on any electrical property) → Transistor → is used in (the component every other modern technology is assembled from, and one nobody ever sees) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
Germanium → is associated with (first, and displaced — its oxide dissolves in water, which the planar process cannot tolerate) → The semiconductor era complete chain
Germanium → is used as (in infrared optics rather than visible emission) → Lighting
Germanium → is used in (the first one, and displaced by silicon on the oxide rather than on any electrical property) → Transistor → is associated with (the device the whole period is about) → The semiconductor era complete chain