What are the substances of semiconductors and conductors?

Semiconductors are generally related to silicon, conductors are metals or electrolyte solutions, etc.

The conductor is generally a low-cost element, the semiconductor is generally silicon, germanium tetravalent element, and the conductor is silver, copper, etc.

PS: Excerpt from Chapter 2 of the 4th Edition of Fundamentals of Analog Electronics.

Introduction to semiconductors.

As the name suggests, a material with conductive properties between a conductor and an insulator is called a semiconductor

Matter exists in various forms, solids, liquids, gases, plasma, and so on. We usually refer to materials with poor or poor electrical and thermal conductivity, such as diamonds, intraocular crystals, amber, ceramics, etc., as insulators. Metals such as gold, silver, copper, iron, tin, aluminum, etc., which conduct electricity and heat well, are called conductors.

The material between a conductor and an insulator can simply be called a semiconductor. Compared with conductors and insulators, the discovery of semiconductor materials was the latest, and it was not until the 30s of the 20th century, when the purification technology of materials was improved, that the existence of semiconductors was truly recognized by the academic community.

Semiconductor definition.

A substance with a resistivity between a metal and an insulator and a negative temperature coefficient of resistance.

The resistivity of semiconductors is about 10-5 107 ohms·m at room temperature, and the resistivity index decreases when the temperature increases.

There are many semiconductor materials, which can be divided into two categories: elemental semiconductors and compound semiconductors according to their chemical composition.

Germanium and silicon are the most commonly used elemental semiconductors; Compound semiconductors include - compounds (gallium arsenide, gallium phosphide, etc.), group compounds (cadmium sulfide, zinc sulfide, etc.), oxides (oxides of manganese, chromium, iron, copper), and solid solutions composed of - and - compounds (gallium aluminum, arsenic, gallium arsenic phosphorus, etc.). In addition to the above-mentioned crystalline semiconductors, there are also amorphous glass semiconductors and organic semiconductors.

What is a conductor.

A conductor is an object that conducts electricity easily, and an object that does not conduct electricity easily is called an insulator. (It is not that objects that can conduct electricity are called conductors, and objects that cannot conduct electricity are called insulators, which is a common mistake made by ordinary people) There are freely moving electrons in metal conductors, and the reason for conducting electricity is free electrons.

Metals such as gold, silver, copper, iron, tin, aluminum, etc., which conduct electricity and heat well, are called conductors.

The differences in the conduction mechanism of semiconductors and metal conductors are: there are two kinds of particles in semiconductors, free electrons and holes, which carry electric current, so that semiconductors conduct electricity; There are a large number of free electrons inside the metal conductor that can move freely, and these free electrons move directionally under the action of the electric field force to form an electric current, which enables the metal to conduct electricity.

Ionic crystals do not conduct electricity and can conduct electricity when melted or dissolved in water. In ionic crystals, ionic bonds are strong and ions cannot move freely, that is, there are no free-moving ions in the crystal, so ionic crystals do not conduct electricity. When ionic compounds are dissolved in water, anions and cations become freely moving ions (or hydrated ions) after being affected by water molecules, and under the action of external electric fields, anions and cations move directionally and conduct electricity.

They are divided by their properties, divided into different types, and their conductivity varies greatly.

It is divided according to their conductive properties, and the conductivity of semiconductors is not particularly good, but the conductivity of conductors is very good.

In general, the resistance of a conductive conductor may become smaller. If the resistance is particularly large, it is a semiconductor.

Conductors are good at conducting electricity, and insulators are not good at conducting electricity. Whereas, semiconductors are between conductors and insulators. There are quite a few properties of silver, and silicon and germanium are the most common semiconductors.

The conductor is a kind of gas gas with very good conductive interference performance. It can't be burned, that is, it has the property of conducting electricity, and then it also has the property of non-conduction. When a certain threshold is reached, it is turned on. Good.

The difference between conductors and semiconductors is the strength of electrical conductivity.

Objects such as germanium, silicon, selenium, gallium arsenide, and many metal oxides and metal sulfides, whose conductivity is between conductors and insulators, are called semiconductors.

Semiconductors have some special properties. For example, the relationship between the resistivity and temperature of semiconductors can be used to make thermistors (thermistors) for automatic control; Its photosensitive and special round digging properties can be used to make photosensitive elements for automatic control, such as photocells, photocells and photoresistors.

Semiconductors also have one of the most important properties, and if trace impurities are properly incorporated into pure semiconductor substances, their conductivity will increase millions of times. This characteristic can be used to manufacture a variety of semiconductor devices for different purposes, such as semiconductor diodes, transistors, etc.

If one side of a semiconductor is made into a p-shaped region and the other side is made into an n-shaped region, a thin layer with special properties is formed near the junction, which is generally called a pn junction. The upper part of the figure shows the diffusion of carriers on both sides of the interface between p-type semiconducting orange refractory and n-type semiconductors (indicated by black arrows). The middle part shows the formation process of the p-n junction, indicating that the diffusion of the carriers is greater than the drift (indicated by a blue arrow, and a red arrow indicates the direction of the built-in electric field).

The lower part is the formation of the PN junction. Represents the dynamic equilibrium of diffusion and drift.