What is Semiconductor?
Published: 2021-06-13 04:10:55

Hi guys, if you are searching for semiconductors then today we are here to fulfill your requirements. In this article, you will find the definition, description, types, examples, and every possible information about [semiconductors](https://www.theengineeringprojects.com/2020/08/introduction-to-semiconductors.html).

The term “semiconducting” was used for the first time by Alessandro Volta in 1782. In 1833, Michael Faraday was a first person to observe a semiconductor. In 1901, the very first semiconductor device, called "cat whiskers," was presented.

Solid-state materials are commonly grouped into three classes: insulators, semiconductors, and conductors. Keep reading the article because we are going to discuss semiconductors in detail.

##What is Semiconductor?

“Semiconductors are materials which have a conductivity between conductors (generally metals) and non-conductors or insulators (such as ceramics).”
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It is a material whose electrical conductivity can be altered (called doping) through variations in temperature, applied fields, or adding impurities. The electrical conductivity of a semiconductor is between that of a good conductor (like copper) and that of an insulator (like rubber). Hence, the name semiconductor.

##Examples of semiconductors

Silicon and Germanium are the best semiconductor materials. These materials have intermediate conductivity ranging between 10-6 to 10-4 Ω -1m-1. Gallium arsenide is the second most common semiconductor and is used in laser diodes, solar cells, and others.

##Description of Semiconductors

Semiconductors are those materials which have electrical properties lies between those of insulator and [conductors](http://hyperphysics.phy-astr.gsu.edu/hbase/electric/conins.html). At room temperature they have:

   * A partially filled valence band
   * A partially filled conduction band
   * A narrow energy gap (1eV)

At higher temperature thermal vibration may break some of the covalent bonds to produce free electrons that can participate in current conduction.

A pure semiconductor is an insulator at 0K. At this temperature, it has no electron in the conduction band. But with the increase in temperature, the electron jumps from valence band to the conduction band. Thus a vacancy of the electron is produced in the valence band which is called a hole and it behaves like a positive charge. So at room temperature, Ge and Si crystal becomes a semiconductor.

The ability of semiconductors to conduct electricity can be greatly improved by replacing or adding certain donor or acceptor atoms to this crystalline structure. That is done by adding a small amount of another element to the base material, either silicon or germanium.

Semiconductors are pure elements and composed of single species of atoms, such as silicon (Si), germanium (Ge), and Tin (Sn) in column IV and selenium (Se) and tellurium (Te) in column VI of the periodic table. At low temperatures some conductors, semiconductors, and insulators may become super-conductors.

##Semiconductor Devices

There are many semiconductor devices. Some of these are as follows:

The two-terminal devices are:

   * [Diode](https://www.theengineeringprojects.com/2018/05/introduction-to-diode.html) (rectifier diode)
   * Gunn diode
   * Laser diode
   * PIN diode
   * Tunnel diode
   * Light-emitting diode (LED)
   * Photo transistor
   * Photocell
   * Solar cell

Three-terminal devices are:

   * Bipolar transistor
   * Field-effect transistor
   * Darlington transistor
   * Unijunction transistor
   * Silicon-controlled rectifier

Four-terminal devices are:

   * Photo coupler
   * Hall effect sensor (magnetic field sensor)