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What you will learn in Semiconductors & Electronics
1. Three Kinds of Material, One Number
Conductor, semiconductor and insulator sound like three sorts of substance. They are three regions of a single quantity, and the whole module follows from that.
2. Deliberate Contamination
One atom in ten million, from the next column of the periodic table, raises silicon's conductivity half a million times over — and decides which kind of charge carries the current.
3. A Barrier Nobody Built
Put p-type against n-type and a voltage appears across the boundary with nothing connected. Everything after this chapter is a consequence of it.
4. There Is No Turn-On Voltage
The famous 0.7 volt knee is an artefact of the axis it is drawn on. Change the axis and the current was there all along.
5. Making Direct Current Out of Alternating
Four steps from a mains sine wave to something a circuit can run on, with every figure measured off the waveform rather than quoted from a formula.
6. One Curve, Two Devices
The transistor as a switch and the transistor as an amplifier are the same graph, read in different places.
7. One Gate Is Enough
Every logic function there is can be built from NAND alone. Four rows is the entire input space, so checking all four is not a test — it is the proof.
8. From One Switch to a Trillion
Twelve orders of magnitude, climbed one rung at a time — and then the chart of what Moore's law predicted against what actually got built.
9. The Gap Decides the Colour
The number the module opened with turns out to say what an LED emits and what a solar cell can see. Same equation, read in both directions.