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Introduction to Semiconductors

Semiconductors: Materials that have electrical conductivity between conductors and insulators. They are fundamental to modern electronics.

Intrinsic Semiconductors: Pure semiconductors without any impurity. Examples include silicon (Si) and germanium (Ge). They have a balanced number of charge carriers (electrons and holes).
Extrinsic Semiconductors: Doped semiconductors that have added impurities to change their electrical properties. They can be categorized into two types:
- n-type Semiconductors: Created by doping intrinsic semiconductors with donor atoms that provide extra electrons, improving conductivity.
- p-type Semiconductors: Formed by doping with acceptor atoms, creating holes (positively charged spaces) that assist charge transfer.

Electrons are negatively charged carriers.
Holes are the absence of electrons and behave like positively charged particles. They are considered as charge carriers in p-type semiconductors.

Doping: The introduction of impurities into a semiconductor to modify its electrical properties. Donor atoms contribute free electrons, while acceptor atoms create holes.
Donor Atoms: Elements such as phosphorus in silicon that provide extra electrons.
Acceptor Atoms: Elements such as boron in silicon that create holes.

A region in a semiconductor diode where mobile charge carriers (electrons and holes) are depleted, creating a region under an electric field that barriers current flow unless enough voltage is applied.

Diode: A semiconductor device that allows current to flow in one direction. They are critical in converting alternating current (AC) to direct current (DC).
Rectifier Diode: Specialized type used for rectifying AC to DC.
Bridge Rectifier: Circuit using four diodes arranged intelligently to convert AC into DC efficiently.

LED: A diode that emits light when current flows through it. They are vital in-display technologies and lighting applications.

Transistor: A semiconductor device used to amplify or switch electronic signals. It consists of three parts: collector, emitter, and base.

Current Amplifier: A circuit that increases the current of a signal without altering its voltage.
Signal Amplifier: Similar to current amplifiers, they boost the strength of a signal to drive loads more effectively.

Forward Bias: Connecting the positive terminal of a voltage source to the p-type material and the negative to the n-type allowing current to flow easily through the junction.
Reverse Bias: Connecting the opposite terminals to inhibit current flow, wide application in power supply systems for controlling current.