IC Semiconductors

What is a semiconductor?

A semiconductor is a type of crystalline substance that is halfway between a conductor and an insulator in terms of electrical conductivity. Semiconductors are used in the production of diodes, transistors, and integrated circuits, among other electronic devices. Because of their compactness, reliability, power efficiency, and low cost, such devices have found widespread use.

They've been used in power devices, optical sensors, and light emitters, including solid-state lasers, as discrete components. They can handle a wide range of current and voltage and, more importantly, they're easy to integrate into sophisticated yet easily manufactured microelectronic circuits.

They serve communications, signal processing, computing, and control applications in both consumer and industrial markets, and will continue to do so in the foreseeable future.

Materials for semiconductors:

Insulators, semiconductors, and conductors are the three basic types of solid-state materials. (Some conductors, semiconductors, and insulators can become superconductors at low temperatures.) The conductivities (and related resistivities = 1/) associated with certain key materials in each of the three groups are shown in the diagram.

Insulators, such as fused quartz and glass, have very low conductivities, on the range of 1018 to 1010 siemens per centimeter, whereas conductors, such as aluminum, have very high conductivities, often between 104 and 106 siemens per centimeter

Semiconductors' conductivities fall somewhere in between these two extremes, and they're usually affected by temperature, illumination, magnetic fields, and minute amounts of impurity atoms. For instance, adding around 10 atoms of boron (a dopant) per million atoms of silicon can boost its electrical conductivity by a thousandfold.

History of semiconductors:

Semiconductor materials have been studied since the early 1800s. The elemental semiconductors are those made up of single atom species, such as silicon (Si), germanium (Ge), and tin (Sn) in column IV of the periodic table, and selenium (Se) and tellurium (Te) in column VI. However, compound semiconductors, which are made up of two or more elements, are abundant.

For example, gallium arsenide (GaAs) is a binary III-V compound made up of gallium (Ga) from column III and arsenic (As) from column V. Mercury indium telluride (HgIn2Te4), an II-III-VI compound, is an example of a ternary compound created by elements from three distinct columns.

They can also be created by elements from two columns, for as aluminum gallium arsenide (AlxGa1 xAs), a ternary III-V compound in which both Al and Ga are from column III and the subscript x refers to the composition of the two elements, ranging from 100% Al (x = 1) to 100% Ga (x = 0). For integrated circuit applications, pure silicon is the most important material, whereas for light emission, III-V binary and ternary compounds are the most crucial.

Electronic characteristics of semiconductors:

Single crystal semiconductor materials are those in which the atoms are organized in a three-dimensional periodic pattern. A simplified two-dimensional model of an intrinsic (pure) silicon crystal with negligible impurities is shown in Part A of the image. In the crystal, each silicon atom is surrounded by four of its closest neighbors. Each atom contains four electrons in its outer orbit, which it shares with four other atoms.

A covalent bond is formed when two electron pairs are shared. The two atoms are held together by the force of attraction between the electrons and both nuclei. Only discrete energy levels are possible for solitary atoms (e.g., in a gas rather than a crystal). When a significant number of atoms are gathered to form a crystal, however, the atoms' interactions cause the discrete energy levels to spread out into energy bands.

The electrons in an insulator or semiconductor crystal will entirely fill a number of energy bands when there is no thermal vibration (i.e., at low temperature), leaving the remainder of the energy bands unoccupied. The valence band is the highest filled band.

The conduction band comes next, separated from the valence band by an energy gap (much larger gaps in crystalline insulators than in semiconductors). This energy gap, also known as a bandgap, is an area in which the electrons in the crystal are unable to possess certain energies. The bandgaps of most significant semiconductors range from 0.25 to 2.5 electron volts (eV). Silicon has a bandgap of 1.12 eV, while gallium arsenide has a bandgap of 1.42 eV. Diamond, on the other hand, has a bandgap of 5.5 eV, making it a good crystalline insulator.

Integrated circuits are made up of semiconductors:

Integrated circuits are the foundation of practically all modern technology. It's a small square or rectangle of semiconductor material, usually silicon, that holds electronic circuits that are laid down or grown to perform computation or other functions. The idea was to embed a large number of transistors and other devices onto a single piece of silicon and construct the interconnections within the silicon.

Electronic components such as transistors, resistors, diodes, inductors, and capacitors were manually connected together on a board before the integrated circuit. By combining components into a single chip of material, the integrated circuit enabled for more powerful, lightweight, and smaller applications.

Why semiconductors?:

Semiconductors use the least amount of energy. It can operate at extremely low voltages. Previously, vacuum tube technology was used to do mathematical operations and compute electronics. As a result, since 1947, when transistor semiconductors were introduced, they have played a significant part in mathematical operations and computing electronics.

Semiconductors take up the least amount of space. It is small enough to fit in your phone or tablet. All electronics operations such as amplification, oscillation, and mathematical operations can be carried out using semiconductor devices such as transistors and diodes.

Semiconductors can be found almost anywhere. Today's era is known as the Silicon Age, because silicon is used in the majority of semiconductors. One of the most significant advantages of semiconductors in electronics is the ability to control the flow of electrons (current) by adjusting the voltage at other terminals.