Key Notes on Examples of Semiconductors

The electrical conductivity of a semiconductor material is somewhere between that of a conductor, such as metallic copper, and that of an insulator, such as glass. As the temperature rises, its resistivity decreases; metals, on the other hand, exhibit the reverse behaviour. By injecting impurities (“doping”) into the crystal structure, the conductivity of the material can be changed in useful ways. A semiconductor junction is formed when two distinct doped regions of the same crystal occur. Diodes, transistors, and most modern electronics are based on the behaviour of charge carriers, which include electrons, ions, and electron holes, at these junctions. Silicon, germanium, gallium arsenide, and elements near the “metalloid staircase” on the periodic table are some examples of semiconductors. Gallium arsenide, the second most prevalent semiconductor after silicon, is used in laser diodes, solar cells, microwave-frequency integrated circuits, and other applications. Silicon is used to make the majority of electrical circuits.

Silicon

Silicon, with the symbol Si and the atomic number 14, is a chemical element. It’s a tetravalent metalloid and semiconductor, and it’s a hard, brittle crystalline solid with a blue-grey metallic sheen. Carbon is above it, and germanium, tin, lead, and flerovium are below it in the periodic table. It has a low reactivity level. Jöns Jakob Berzelius was the first to create and characterise it in pure form, owing to its great chemical affinity for oxygen. The oxides in it belong to the silicate family of anions. It has the second highest melting and boiling temperatures of all metalloids and nonmetals, with 1414 °C and 3265 °C, respectively. Silicon is the eighth most abundant element in the universe by mass, yet it is extremely rare in the Earth’s crust as a pure element. As various forms of silicon dioxide (silica) or silicates, it is most widely distributed in space as cosmic dust, planetoids, and planets. Silicate minerals make up more than 90% of the Earth’s crust, making silicon the second most plentiful element after oxygen (approximately 28% by mass). Silicon is a naturally occurring element with a 400-year residence time in the world’s oceans when it hasn’t been there before.

Silicon comes from the Latin word silex, which means “hard stone” or “flint.” Jöns Jacob Berzelius, a Swedish scientist, was the first to isolate and characterise amorphous elemental silicon in 1824. In the year 1811, impure silicon was discovered. Electrolysis was used to create crystalline elemental silicon in 1854. Silicon, in the form of rock crystal, was known to the predynastic Egyptians, who utilised it for beads and miniature vases, as well as the early Chinese and most other ancients. Both the Egyptians and the Phoenicians produced silica-containing glass, dating back to at least 1500 BCE. Many of the naturally occurring compounds known as silicates were undoubtedly utilised in various types of mortar by the first humans for the construction of houses.

Germanium

With the symbol Ge and atomic number 32, germanium is a chemical element. It’s a glossy, hard-brittle greyish-white metalloid in the carbon group, chemically related to silicon and tin. Pure germanium resembles elemental silicon in appearance. In the natural world, germanium, like silicon, interacts with oxygen and creates complexes. Germanium was found relatively late in the history of chemistry due to its rare appearance in high concentrations. In terms of relative abundance of elements in the Earth’s crust, germanium ranks near the fifty-fifth position. Dmitri Mendeleev named the element ekasilicon in 1869 after predicting its existence and some of its properties based on its position on his periodic table. Clemens Winkler discovered the new element in a rare mineral called argyrodite in 1886, together with silver and sulphur. The combining ratios in compounds accorded with Mendeleev’s predictions for a silicon relative, despite the fact that the new element resembled arsenic and antimony in appearance. Germany was Winkler’s inspiration for the element’s name. Today, sphalerite (zinc’s principal ore) is the most common source of germanium, but it can also be found in silver, lead, and copper ores.

Gallium arsenide

Gallium arsenide is a type III/V semiconductor that has a high electron mobility and a high saturation electron velocity relative to silicon, allowing gallium arsenide transistors to operate at frequencies exceeding 250 GHz.

Because of their broad bandgap, gallium arsenide devices are resistant to heat. Additionally, these devices produce less noise than silicon devices, particularly at high operating frequencies.

Monolithic microwave integrated circuits, microwave frequency integrated circuits, infrared light-emitting diodes, solar cells, laser diodes, and optical windows are all examples of devices that can be made with gallium arsenide. Unlike many other semiconductors, GaAs has a straight bandgap, which means it can efficiently emit light. It can be used in optical windows and space electronics in high-power applications since it is a direct bandgap material that resists radiation damage. It also serves as an electrical substrate, providing natural circuit and device isolation. As a result, it can be used in millimetre-wave and microwave integrated circuits. The Opportunity and Spirit rovers, which are now exploring Mars’ surface, are powered by solar cells made of GaAs. Solar arrays made of GaAs are found in a variety of solar automobiles. To detect X-rays, GaAs diodes are employed.

Conclusion

Gapless semiconductors and semiconductors with a narrow energy gap, g 0.1 eV, have unique features that open up a wide range of applications. The extraordinary sensitivity of these materials’ band structures to external effects like magnetic fields, electromagnetic radiation, pressure, temperature, and contaminants makes them exceedingly valuable.

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.