We explain what an electrical semiconductor is, its types, applications and examples. In addition, conductive and insulating materials.

The most widely used semiconductor is silicon.

What is a semiconductor?

Semiconductors are materials capable of acting as electrical conductors or as electrical insulators, depending on the physical conditions in which they are found. These conditions usually involve temperature and the Pressure, the incidence of radiation or the intensities of the electric field or magnetic field to which the material is subjected.

Semiconductors are made up of chemical elements very varied among themselves, which in fact come from regions other than the Periodic table, but they share certain chemical traits (generally they are tetravalent), which give them their particular electrical properties. Currently, the most widely used semiconductor is silicon (Si), particularly in industry electronics and of the computing.

Along with insulating materials, semiconductors were discovered in 1727 by the English physicist and naturalist Stephen Gray (1666-1736), but the laws that describe their behaviors and properties were described much later, in 1821, by the famous German physicist Georg Simon. Ohm (1789-1854).

Semiconductor applications

Semiconductors are especially useful in the electronics industry, since they allow driving and modulating the electric current according to the necessary patterns. For that reason, it is usual that they are used to:

  • Transistors
  • Integrated circuits
  • Electric diodes
  • Optical sensors
  • Solid state lasers
  • Electric drive modulators (like an electric guitar amp)

Types of semiconductors

Semiconductors can be of two different types, depending on their response to the physical environment in which they are:

Intrinsic semiconductors

They are made up of a single type of atoms, arranged in molecules tetrahedral (that is, four atoms with a valence of 4) and their atoms joined by covalent bonds.

This chemical configuration prevents movement free from electrons around the molecule, except for an increase in temperature: then the electrons take part of the Energy available and “jump”, leaving a free space that is translated as a positive charge, which in turn will attract new electrons. This process is called recombination, and the amount of heat required for this depends on the chemical element in question.

Extrinsic semiconductors

These materials allow a doping process, that is, they allow some type of impurities to be included in their atomic configuration. Depending on these impurities, which can be pentavalent or trivalent, semiconductor materials are divided into two:

  • N-type extrinsic semiconductors (donors). In these types of materials, the electrons outnumber the holes or carriers of free charge ("spaces" of positive charge). When a potential difference is applied to the material, the free electrons move to the left of the material and the holes then to the right. When the holes reach the extreme right, electrons from the external circuit enter the semiconductor, and the transmission of electrical current occurs.
  • Extrinsic P-type semiconductors (acceptors). In these materials, the added impurity, instead of increasing the available electrons, increases the holes. Thus, we speak of added acceptor material, since there is a greater demand for electrons than availability and each free “space” where an electron should go serves to facilitate the passage of current.

Examples of semiconductor materials

Semiconductors serve as modulators of electrical transmission.

The most common and used semiconductors in the industry are:

  • Silicon (Si)
  • Germanium (Ge), often in alloys silicon
  • Gallium Arsenide (GaAs)
  • Sulfur
  • Oxygen
  • Cadmium
  • Selenium
  • Indian
  • Other chemical materials resulting from the combination of elements from groups 12 and 13 of the periodic table, with elements from groups 16 and 15 respectively.

Conductive materials

Unlike semiconductors, whose electrical conduction properties vary, conductive materials are always ready to transmit the electricity, due to the electronic configuration of its atoms. This conductivity can fluctuate and be affected to some degree by the physical state of the environment since the electric conductivity it is not absolute.

Examples of conductive materials are the vast majority of metals (iron, mercury, copper, aluminum, etc.) and the Water.

Insulating materials

Finally, insulating materials are those that resist the conduction of electricity, that is, that prevent the passage of electrons and they are useful, therefore, to protect themselves from electricity, to prevent it from running a free course, or from short-circuiting. Insulators also do not insulate one hundred percent efficiently, They have a limit (breakdown voltage) above which the energy is so intense that they cannot maintain their condition as insulators and, therefore, transmit electric current, at least in certain degree.

Examples of insulating materials are plastic, ceramics, glass, wood and paper.

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