How do semiconductors work in the microscopic? What is the principle of semiconductors

Metal wires, from left to right or from right to left, can conduct current in both directions, so they are called conductors.

Plastics, on the other hand, cannot conduct current in both directions, so they are called non-conductors or insulators.

Diode Semiconductor device with two electrodes Semiconductors are devices that can make current flow from left to right at very low voltage vF, but from right to left, you have to use high-voltage VR to gradually turn on.

Because it is one-way and easy to conduct, it is neither a conductor nor a non-conductor, but only half a one-way conductor.

That's why it's called semiconductors.

The diode is the most basic and simple semiconductor, and its special property comes from the sandwich structure, that is, the diode.

The structure is composed of 3 4 5 valence electron elements, the common 3 valence electron element is boron, the 4 valence electron element is silicon, and the 5 valence electron element is phosphorus, and these three different elements are sequentially combined into a sandwich layer at about 1200 degrees C, heated at high temperature, fused, and diffused into one, resulting in one more valence electron on one side than the tetravalent electron silicon element in the middle main shell, and one less valence electron on the other side than the tetravalence electron silicon element in the middle middle main shell, so the end result is that only a very small voltage vf is required for one more valence electronIt can flow smoothly to the other side, and it is very difficult to circulate to the other side without a valence electron on the other side (unless there is a high voltage VR), so the so-called semiconductor characteristics are formed, because there are only positive and negative (p n) poles in total, so it is called a diode or a diode, also known as a diode.

Electronic part numbers that start with 1n are either diodes or diodes.

You're involved in analog electronics.

Macroscopically, semiconductors are unidirectionally conductive, and the reason for this is that there is a p-n junction in them.

If the pentavalent elements are mixed in the semiconductor, the n-type semiconductor will be formed, and if the trivalent elements are mixed to form the p-type semiconductor, then if the pentavalent and trivalent elements are mixed at both ends of the semiconductor, the pn junction will be formed.

First of all, it is important to know that the two forces inside the semiconductor, the diffusion force and the electric field force (the internal electric field is formed at the pn junction), are equal without applying an external voltage, and we call this state dynamic equilibrium. (Diffusion force = electric field force).

If a forward voltage is applied to the PN junction, the internal electric field formed by the PN junction will be weakened (diffusion force "electric field force"), and if a reverse voltage is applied to the opposite voltage, the inner cell will be strengthened (diffusion force "electric field force").

Therefore, only under the condition of applying a forward voltage (diffusion force and electric field force), the free electrons located in the n region can move due to the diffusion force to form an electric current and conduct electricity (in fact, the holes in the p region will also move due to the diffusion force to form a current, so I don't mention that for fear of confusion).

On the other hand, when a reverse voltage (diffusion force is added), the free electrons are not affected or subjected to very little diffusion force, and there is no way to move to form an electric current. This is why there is a unidirectional conductivity of semiconductors.

You may ask why electrons cannot move to form an electric current due to the internal electric field of the p-n junction, because the internal electric field causes the free electrons inside the semiconductor to move in the opposite direction to the direction of the free electrons in the wire with an applied forward voltage. Anyway:

The electric field force of the p-n junction suppresses the diffusion force.

Semiconductor principle: At a certain temperature, the generation and recombination of electron-hole pairs exist at the same time and reach dynamic equilibrium, and the semiconductor has a certain carrier density and thus a certain resistivity. As the temperature increases, more electron-hole pairs will be generated, the carrier density will increase, and the resistivity will decrease.

Therefore, the main principle of semiconductors is the movement of electrons.

Semiconductor Applications:

Semiconductors are mainly used to make semiconductor devices, there are many types, and the application is extremely wide, and now the bright electronic circuits are basically inseparable from semiconductor devices, the computers and mobile phones we use, the integrated circuits in them are made of semiconductors, mainly using silicon as materials. Semiconductor devices are also used in the circuits of various electrical appliances. It is widely used in power systems (such as thyristors) and optoelectronic fields (lasers, LEDs, CCDs, camera lenses).

At present, the widely used semiconductor materials include germanium, silicon, selenium, gallium arsenide, gallium phosphide, indium antimonide, etc., among which the production technology of germanium and silicon materials is more mature and used more. Components made of semiconductor materials, integrated circuits, etc. are important basic products in the electronics industry, and have been widely used in all aspects of electronic technology. The production and scientific research of semiconductor materials, devices and integrated circuits have become an important part of the electronics industry.

Principle: At very low temperatures, the valence band of the semiconductor is a full band (see band theory), after being thermally excited, some electrons in the valence band will cross the forbidden band into the space band with higher energy, and the presence of electrons in the band becomes the conduction band, and the lack of an electron in the valence band forms a positively charged vacancy, called a hole. Hole conduction is not an actual motion, but an equivalence.

When electrons conduct electricity, the holes of equal charge move in their opposite direction. They produce directional motion under the action of an external electric field to form macroscopic currents, which are called electron conduction and hole conduction, respectively. This hybrid conduction, which is formed due to the generation of electron-hole pairs, is called intrinsic conduction.

The electrons in the conduction band fall into the holes, and the electron-hole pairs disappear, which is called recombination.

The energy released during recombination becomes electromagnetic radiation (luminescence) or thermal vibration energy of the crystal lattice (heat generation). At a certain temperature, the generation and recombination of electron-hole pairs exist simultaneously and reach dynamic equilibrium, at which point the semiconductor has a certain carrier density and thus a certain resistivity. As the temperature increases, more electron-hole pairs are generated, the carrier density increases, and the resistivity decreases.

A substance whose ability to conduct electricity is between that of a conductor and an insulator.

The principle of electrical conductivity is to obtain two kinds of semiconductors, namely n-type and p-type semiconductors, after doping in pure semiconductors.

As a result of doping, two elements involved in electrical conductivity are produced within the two classes of semiconductors: free electrons and holes. If two types of doped semiconductors are combined together through a special process, the movement phenomena such as diffusion, drift and recombination of electrons and holes will occur, and this movement phenomenon will lead to the formation of PN junctions at the junction of the two types of semiconductors.

The PN junction is the basis for the electronic devices. It has a lot of properties. For example, the diodes, transistors, field effect transistors, integrated circuits, etc. we use now.

Sorry, I didn't say it all, if you don't have a foundation in electronic technology, you won't understand. It is recommended that if you want to learn well, you have to study systematically. There is still a lot of knowledge to follow, I wish you a good study.

Energy belt theory, to put it simply:

Metals, valence bands and conduction bands coincide.

The insulator, the barrier between the valence band and the conduction band is large.

In semiconductors, the potential barrier between the top of the valence band and the bottom of the conduction band is not so large, allowing certain electrons to jump from the valence band to the conduction band to conduct electricity to generate current, and its conductivity is greatly affected by the external environment.

Semiconductors are one that comes at a specific temperature since.

The conductivity of semiconductors is between DAO conductor and insulator, and the more commonly used ones are DAO silicon and germanium; Pure half-page conductors can only be righted.

Raw materials, nothing special. It is different after hybridization, it has unidirectional conductivity. This is because of the presence of the p-n junction, weakening the p-n junction electric field will turn on, and vice versa.

Taking silicon as an example, the inclusion of trivalent boron forms holes are denoted by P; The indium that is involved in the five pieces forms free electrons, which are denoted by n; When p-n is combined, diffusion and drift movements occur at the same time, and as a result, the immovable charge forms a p-n junction electric field.

Whether from the perspective of technology or economic development, the importance of semiconductors is very huge. The core unit of most electronic products, such as computers, mobile** or digital voice recorders, is closely related to semiconductors.

Name implies! Semiconductors are materials that sit between conductors and insulators! Most of the commonly used ones in our door are silicon and germanium!

You can refer to the principles and construction of semiconductors"Basic semiconductors"One book! I won't go into detail here!

From the simplest semiconductor diodes to today's VLSI circuits, semiconductors have only gone through a few decades!

What used to be a single tube can be made into millions of components today! If you compare it with an electronic vacuum tube, it is even more amazing!

Take an early set of computers, for example! A six-story piece of equipment is a cigarette case today!

The unit characteristics of semiconductors are diodes, transistors and various derived components with different characteristics!

It is needed for all rectification, voltage regulation, detection, luminescence, receiving, amplification, arithmetic, and storage in the circuit!

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 characteristics 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.

When one side of a semiconductor is made into a p-type region and the other side is made into an n-type region, a thin layer with special properties is formed near the junction, which is generally called a p-n junction. The upper part of the figure shows the diffusion of carriers at the interface between p-type semiconductors 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.