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Learning path: Semiconductors

The concepts to learn before Semiconductors, in order. Each step links to its page and, where one exists, its quiz.

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Your path

  1. AtomsDirect prerequisite

    An atom is the smallest unit of an element that keeps that element's chemical identity. Every atom has a tiny, dense nucleus of protons and neutrons, which holds nearly all of its mass, surrounded by electrons that fill almost all of its volume. The number of protons fixes which element the atom is; changing the number of electrons makes an ion, and changing the number of neutrons makes a different isotope.

    Take the Atoms quiz

  2. ElectricityDirect prerequisite

    Electricity is the behaviour of electric charge, and an electric current is charge flowing round a complete circuit, measured in amperes. A battery's potential difference (voltage) pushes the current, resistance opposes it, and for many materials they are linked by Ohm's law, V = IR. Circuits transfer energy at a rate P = IV; resistors add in series and combine as reciprocals in parallel. Mains electricity can kill and is never used for experiments.

    Take the Electricity quiz

  3. Semiconductors such as silicon conduct electricity better than insulators but far less than metals, because only a small energy gap separates their filled and empty electron bands. Adding tiny amounts of impurity (doping) creates n-type material, rich in electrons, or p-type material, rich in holes. Joining the two makes diodes and transistors — the switches and amplifiers from which every computer chip is built.

    Take the Semiconductors quiz

Where to go next

Concepts that build directly on Semiconductors:

  • Quantum Computing: Quantum computers process information with qubits, which can be in superpositions of 0 and 1 and can be entangled, so n qubits can hold a superposition of 2ⁿ combinations. That does not mean they try every answer at once: a measurement reveals only a little information, so useful quantum algorithms — such as Shor's 1994 factoring algorithm — must be cleverly designed. Today's machines have hundreds of error-prone qubits; large, error-corrected quantum computers remain a goal, not a reality.