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Electronics Tutorial

Semiconductors Basics

Semiconductors are essential components of modern electronics, powering devices that have become an integral part of our daily lives. These materials have unique electrical properties that make them highly versatile in various applications, ranging from transistors and integrated circuits to solar cells and light-emitting diodes.

Definition

Semiconductors are materials that possess a conductivity level between conductors (such as metals) and insulators (such as rubber or glass). They are typically crystalline in structure, with their electrical behaviour heavily influenced by the arrangement of atoms within the crystal lattice.

Semiconductor types

The behaviour of semiconductors is primarily governed by the movement of electrons. There are two types of semiconductors 

  1. Intrinsic Semiconductor: Intrinsic semiconductors have a balanced number of electrons and holes (electron deficiencies) at room temperature, resulting in limited electrical conductivity.
  2. Extrinsic Semiconductor: Semiconductors can be intentionally modified to improve their electrical conductivity through a process called doping. Doping involves introducing impurity atoms into the semiconductor crystal, which can either donate extra electrons (n-type doping) or accept electrons (p-type doping). N-type semiconductors exhibit an abundance of electrons, whereas p-type semiconductors showcase an abundance of holes.

Semiconductor devices

  • Diode: The interaction between n-type and p-type semiconductors gives rise to a fundamental device known as a diode. A diode allows current flow in one direction while blocking it in the opposite direction. This property forms the basis for rectification and signal modulation in electronic circuits.

  • Transistor: Transistors are three-layered structures made up of two layers of one type of semiconductor (either p or n) sandwiching a layer of the opposite type i.e. NPN or PNP. They act as amplifiers or switches, controlling the flow of current through the device. Transistors are the building blocks of integrated circuits (ICs), enabling the creation of complex electronic systems.

Advancements in semiconductor technology have led to the development of smaller, faster, and more efficient electronic devices. Moore’s Law, an observation made by Intel co-founder Gordon Moore, states that the number of transistors on an integrated circuit tends to double approximately every two years. This exponential growth has propelled the semiconductor industry forward, revolutionising fields such as computing, telecommunications, and consumer electronics.

In conclusion, semiconductors are critical components in modern electronics, offering a wide range of electrical properties that can be harnessed through doping and device fabrication. The ability to control the behaviour of semiconductors has paved the way for technological advancements, making them an integral part of our increasingly interconnected world.

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