Semiconductors Definition

Any of a group of crystalline solids that fall halfway between a conductor and an insulator in terms of electrical conductivity. Semiconductors are used to make diodes, transistors, and integrated circuits, among other electronic components. Compactness, reliability, power efficiency, and low cost have all helped these devices find widespread use. They’re 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 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 industries, and they will continue to do so in the foreseeable future. Semiconductor devices have a variety of useful qualities, including changeable resistance, the ability to pass current in one direction more easily than the other, and the ability to react to light and heat. Signal amplification, switching, and energy conversion are among the functions they perform. As a result, they’re used in nearly every industry, and the companies that make and test them are thought to be good markers of the economy’s health.

Fermi Level in Semiconductors

At 0°K, the Fermi Level is the energy level occupied by the electron orbital. The conductivity of different materials is determined by the level of occupancy. The orbital occupancy of solid materials, such as metals, can be determined using an approximation based on the crystalline structure. The combination of these orbitals and the energy level determines whether the material is an insulator, semiconductor, or conductor. The orbitals are classified based on their energy. The valence electron band is formed when lower energy orbitals join, whereas the conduction band is formed when higher energy orbitals combine. The energy gap is the distance between the valence and conduction bands; the higher the energy gap, the more energy is required to transport an electron from the valence to the conduction band.

Conduction Band and Valence Band in Semiconductors

The conduction band is the lowest range of available electronic states in electrical insulators and semiconductors. The valence band lies below the Fermi level, while the conduction band is above it on a graph of a material’s electronic band structure. When electrons are stimulated in semiconductors, such as by ionising radiation, they can reach the conduction band (i.e., they obtain energy higher than E_gap). Diamond, for example, is a wide-band gap semiconductor with a great potential as an electrical device material (E_gap = 5.47 eV). On the other hand, due to the narrow band gap energy of germanium (E_gap = 0.67 eV), the detector must be operated at cryogenic temperatures. Because conduction occurs in one or more partially filled bands that have features of both the valence and conduction bands, the distinction between the valence and conduction bands is nonsensical in metals.

Holes and Electrons in Semiconductors

In semiconductor materials, carriers are in charge of current. An atom with a hole has no electron at a specific location. A hole can be transmitted from atom to atom in a semiconductor material, while not being a physical particle in the same way that an electron is. Bands or shells define the energy levels at which electrons circle the nucleus. When an electron moves from the valence band into the conduction band (the shell outside the closed shells that is partially or totally filled with electrons), a hole forms in the atom (the outer “cloud” from which electrons most easily escape from, or are accepted by, the atom).

In any semiconductor substance, both electrons and holes exist. Electrons flow from negative to positive, while holes “flow” from positive to negative. Majority carriers are those with the most charge carriers, while minority carriers are those with the fewest. Electrons make up the majority of carriers in n-type semiconductors, whereas holes make up the minority. The opposite is true for p-type semiconductors.

Conclusion

The electrical characteristics of semiconductors are unique. A conductor is something that conducts electricity, while an insulator is something that doesn’t. Semiconductors are materials that have properties that fall in the middle of the spectrum. Semiconductors are used to make integrated circuits (ICs) as well as electronic discrete components like diodes and transistors. Silicon and germanium are common elemental semiconductors. One of these is silicon, which is well-known. The majority of integrated circuits (ICs) are made from silicon. Gallium arsenide and indium antimonide are two examples of common semiconductors.

Semiconductors are used to regulate equipment in a range of industries, including maintaining a comfortable room temperature, enhancing vehicle safety, and providing laser treatment in cutting-edge medical care, among others. Furthermore, developments in semiconductor technology have resulted in increased system efficiency, miniaturisation, and energy savings, all of which contribute to the preservation of the global environment, as well as a safer and more comfortable existence and a successful future. In the nineteenth century, semiconductors were found. Transistor technology was developed in the 1940s. Radios that had previously relied on vacuum tubes were drastically reduced in size and became portable.