In simple terms
A semiconductor is a material whose ability to conduct electricity falls between that of a true conductor, like copper, and an insulator, like glass, and crucially, can be controlled. [1] Silicon is by far the most common semiconductor material used in electronics.
How it works
Pure silicon is a fairly poor conductor on its own. Engineers change that by doping it, deliberately introducing tiny, precisely controlled amounts of other elements into the silicon’s crystal structure. [2] Some dopants add extra free electrons, creating what is called n-type silicon; others create a shortage of electrons, called p-type silicon. Joining n-type and p-type regions together creates junctions that control the direction and flow of electric current, which is the basic building block of a diode or transistor. [1]
A transistor is essentially a tiny electrically controlled switch built from these junctions. A modern computer chip packs billions of transistors into an area smaller than a fingernail, wiring them together to perform logic and store data. [2]
Why it matters
Semiconductors are the reason electronic devices can be made small, reliable, and mass-produced cheaply. Before transistors, equivalent switching was done with bulky vacuum tubes, which were power-hungry, fragile, and could not be packed densely. [1] The ability to manufacture semiconductors at enormous scale and shrinking size is what has driven decades of growth in computing power.
Where you’ll see it
- The processor and memory chips inside every computer and smartphone
- Solar panels, which use semiconductor material to convert sunlight into electricity
- LED lighting, where semiconductor junctions emit light directly
- Sensors in cars, appliances, and medical devices
Example
A smartphone’s main processor is a single piece of doped silicon containing billions of transistors, manufactured in layers far thinner than a human hair.
Often confused with
A transistor is a device built from semiconductor material; a semiconductor is the material itself. Saying a chip “is a semiconductor” is loose shorthand for saying it is built from semiconductor materials, the way calling a car “steel” would be shorthand for what it is made of.
Key facts
- Semiconductors conduct electricity better than insulators but far less readily than conductors like copper, and their conductivity can be adjusted.1
- Adding small amounts of other elements, a process called doping, changes how many charge carriers a semiconductor has and lets engineers control its electrical behavior precisely.2
- Silicon is the most widely used semiconductor material because it is abundant, inexpensive to purify, and chemically stable.1
- Transistors, the switches that make up a computer chip, are built from semiconductor material and can number in the billions on a single modern chip.2
In the news
Quick checkWhat makes a semiconductor different from an ordinary electrical conductor like copper wire?Show answer
A semiconductor's conductivity can be deliberately controlled, including by doping it with other elements, while a conductor like copper simply conducts electricity at a fixed, high rate that is not practically tunable.
Sources
- Encyclopaedia Britannica. Semiconductor. Undated (accessed 1 November 2026)
- IBM. What Is a Semiconductor?. Undated (accessed 1 November 2026)
Editorially reviewed by Last reviewed November 1, 2026Researched and drafted with AI assistanceReport an issue