Types of semiconductors: definition, properties and classification, applications

The prevalence of various types of semiconductors (PP) in nature is great, but no less materials with unique properties are created by adding some chemical elements to others. New substances are given additional useful qualities that expand the scope of application. Semiconductor materials are used both in general construction industries and in the electronics industry.

Definition and properties

Semiconductors are substances that have weakly pronounced properties of the electrical permeability of metals. and insulators at the same time, there is a dependence of the current movement on temperature, radiation and concentration impurities. The semiconductor group appears to be more materials than metals and dielectrics combined. The available properties of substances are unique:

1. The specific electrical resistance of PP decreases with heating of the body, in contrast to metals, where an increase in temperature causes an increase in resistance. As a result, the conductivity increases. When cooled to absolute zero - minus 273 ºC, PPs acquire the ability to become insulators, dielectrics.
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2. One-sided permeability on contact 2 of semiconductors - this property was the impetus for the creation of rectifier devices: thyristors, diodes and transistors.
3. The appearance of an electric driving force under certain conditions: when the semiconductor contacts are heated, a thermal current appears, and lighting causes a voltage of the photoelectric effect. PP converts solar energy into electric current, and a metal object does not have this property.
4. An increase in conductivity is achieved by introducing an impurity, another chemical element, into the pure crystal lattice of PP. Such substances will be phosphorus, boron and other additives to silicon.

Due to their specific properties, the use of semiconductor materials is extensive: microelectronics, industrial production of machines, and some types of PP are raw materials for construction materials. There are several types of elements, they have different purposes and individual design features.

Types and division of semiconductors

There are many types of PP, and for convenience they are classified according to various criteria. The largest delimitation of semiconductor types is made by composition:

1. Simple materials: crystalline chemical elements selenium Se, silicon Si, germanium Ge have occupied their own niche use and are applied independently, unlike others, which are more often added with alloying additives to obtain composite PP. These are the elements antimony Sb, carbon C, tellurium Te, boron B, iodine I, sulfur S.
2. Complex semiconductor materials - they include chemical combinations in the amount of 2, 3 or more names. PP, consisting of two units, are called binary and distinguish a component, the metal features of which appear weaker: sulfides, if there is sulfur, tellurides (Te), arsenides (As), carbides ©, selenides (Se).
3. Metal oxides - tungsten, cadmium, titanium, copper, molybdenum and others. This group includes compositions based on barium titanate, zinc and other inanimate compounds with small additives.
4. Organic semiconductors are dyes or natural pigments in the form of amorphous and crystalline powders, films.

According to the possession of certain properties, PCBs are divided into diodes, transistors and thyristors. The first ones include 2 crystals of semiconductors of different permeability. The design is made point-like - from silicon and a metal needle, and flat - an alloy of germanium and indium.

Transistors consist of 3 PPs: 2 have an equal ability to pass current, and the third has conductivity with the opposite value. The elements of the device are called the base, collector and emitter. Used as amplifiers for electrical signals.

Thyristors are current motion converters. They differ from transistors in purpose: they cannot change the current: their function is to switch the conductivity to high or low.

Application of universal materials

For the first time, PP in electrical engineering began to be used for the manufacture of selenium AC rectifiers. Since then, progress has made great strides, and today devices using semiconductor materials are ubiquitous. Here is some of them:

• germanium and silicon valves in integrated circuits of the radio-electronic industry - miniature transistors, resistors and diodes, high-voltage rectifiers for DC transmission lines;
• variators - stabilizers of various voltages and speed controllers of high-frequency electric motors;
• thermistors (thermistors) - they have a high modulus of temperature resistance and are used in automation and radio electronics devices;
• photocells and light-emitting diodes based on silicon and germanium are used in solar batteries to convert natural radiation energy into electric current, including in space;
• varistors are nonlinear resistances, they are used as protection against limit voltage values, its stabilization in TVs and displays;
• organic semiconductors are indispensable in complex physicochemical systems and biological tissues: high radiation resistance allows them to be used in outer space, OLED TVs, monitors and displays.

Electrical devices are the main, but not the only purpose of semiconductor materials. Silicon - the content in the earth's crust is 30%, therefore the element is also used for prosaic purposes.

In metallurgy, Si is used to remove from oxygen melts and giving compositions of iron and non-ferrous metals increased reliability against corrosion, increased strength. Excessive silicon causes brittleness.

The production of Si-organic compounds and silicides, the cement, glass, ceramic and electrical industries also use a semiconductor. In total, there are more than 20 areas of application of PP, with their help they solve the issues of generation and transmission of various types of energy, the creation of heat and cold, and the implementation of other processes.