Semiconductors

One common semiconductor material, silicon, is far more widely used in electronics than germanium, partly because it can operate at much higher temperatures. Semiconductors are crystalline materials with electrical resistivity values between conductors and insulators, whose conductivity can be altered through doping with impurities like arsenic or phosphorous to create N-type (excess electrons) or P-type (electron vacancies) materials. Semiconductor devices, such as diodes, transistors, and integrated circuits, leverage these properties to control electron flow in circuits.

A diode, a two-terminal device with an anode and cathode, primarily permits current flow in one direction, making it useful as a rectifier to convert AC to DC. Specialized diodes include Zener diodes for voltage regulation and Light-Emitting Diodes (LEDs) that produce light when current passes through them. Logic circuits, fundamental to digital electronics, have binary inputs and outputs, performing functions like AND, OR, and NOT gates, and can be constructed from various binary devices including solid-state diodes and transistors.

A transistor is an active semiconductor device with at least three terminals (base, emitter, collector), capable of amplifying current. Integrated circuits (ICs), often called chips, are electronic circuits built on a semiconductor substrate, typically silicon. ICs are classified by transistor type (bipolar or MOS) and integration scale: Small-Scale Integration (SSI) with fewer than 10 transistors, Medium-Scale Integration (10-100), Large-Scale Integration (LSI) with 100-1,000, and Very-Large-Scale Integration (VLSI) with more than 1,000 transistors. ICs can be analog, digital, or hybrid, offering virtually limitless functions.