Is the conductivity of semiconductors the same in different directions?

It's the same. The ability of an object to conduct an electric current is called conductivity. The conductivity of various metals varies, and generally silver has the best electrical conductivity, followed by copper and gold.

The conductivity of a solid refers to the remote migration of electrons or ions in a solid under the action of an electric field, usually dominated by a type of charge carrier, such as: electronic conductor, conduction with electron carriers as the main body; ionic conduction, conduction with ion carriers as the main body; Hybrid conductors with both carrier electrons and ions. In addition, some electrical phenomena are not caused by carrier migration, but are caused by solid polarization induced by electric fields, such as dielectric phenomena and dielectric materials.

Ability of an object to conduct electricity: Generally speaking, metals, semiconductors, electrolyte solutions or molten electrolytes, and some non-metals can conduct electricity. The ability of a non-electrolyte object to conduct electricity is determined by the number of free electrons in the outer shell of its atoms and its crystal structure, for example, metals are easy to conduct electricity if they contain a large number of free electrons, while most nonmetals are not easy to conduct electricity due to the small number of free electrons [1].

Graphite conducts electricity, while diamond does not, which is due to their different crystal structures. Electrolytes are conductive because ionic compounds are dissolved or melted to produce anions and cations, which make them electrically conductive.

Chinese name. Electrical conductivity.

Foreign name. electric conductivity significance. The property of an object conducting an electric current.

Material. Some metals, semiconductors, electrolyte solutions.

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Non-conductive solids analyze conductive parameters.

Theory. The earliest theory of metal conductivity is the Truder-Lorentz theory, which is based on classical theory. It is assumed that there are free electrons in metals, which, like ideal gas molecules, obey the classical Boltzmann statistic, and under equilibrium conditions, they are in constant motion, but have an average velocity of zero.

In the presence of an external electric field, the electrons gain acceleration a along the direction of the electric field force, resulting in directional motion, and the electrons lose their directional motion by colliding with the ions that make up the crystal lattice to achieve energy exchange, so that there is an average drift velocity l at a certain electric field strength [2]. According to the classical theory, the contribution of free electrons to the heat capacity of the metal should be comparable to the heat capacity of the lattice vibration, but it was not observed experimentally, and this contradiction was solved after the realization that the electrons in the metal should obey the quantum Fermi statistical law. It is precisely in order to solve this contradiction that, combined with the development of quantum mechanics, we began to systematically study the movement of electrons in the periodic field of crystals, thus gradually establishing the band theory.

According to the band theory, the electrons moving in a strictly periodic potential field are kept in an eigenstate, and the electron motion is not "resisted", but when the atomic vibration, impurity defects and other reasons make the crystal potential field deviate from the periodic field, the electron motion is collided and scattered, so that the free path of the electrons in the crystal is correctly explained.

The electrical conductivity of semiconductors is weaker than that of conductors, which is detailed below:

1. The conductivity of semiconductors is not the same as that of conductors, and the conductivity of semiconductors is weaker than that of conductors, but stronger than that of insulators or bipolar conductivity. In the band structure model, the conductivity of a metal is determined by the mobility of electrons near the Fermi level. The conductivity of a semiconductor is determined by the common mobility of the holes near the top of the valence band and the electrons at the bottom of the conduction band.

2. The effective masses of electrons and holes are not equal, and the effective masses of electrons and holes in the same band are equal; What I mean by this is that the effective mass of the conduction band electron is not equal to the effective mass of the valence band holes, so the conductivity of the two is to be discussed separately. The electrical conductivity of semiconductors is weaker than that of conductors, and semiconductors only conduct electricity in the molten state.

3. When the mechanical temperature is zero, theoretically the electrons in the valence band occupy all positions. Under the action of an external electric field, no position shift occurs and no current is generated. In bandgap, there are no electrons and no current is generated.

Theoretically, the current generation depends on the conduction band. There are no electrons in the conduction band of a semiconductor. When the electrons in the valence band absorb energy, they jump to the conduction band.

There will also be holes in the valence band. In the case of an external electric field, they will transform into electrons in the conduction band and electrons in the valence band.

4. The valence band electrons in the conductor are not all-potent, and they directly produce the current under the action of the external field. The above is a simple concept. The fundamental difference between electron-hole conduction in semiconductors and electron conduction in conductive metals does not consider the effects of defects, etc.

For an ideal material, the electrical conductivity depends on the quantity and mobility involved in the conductivity. Therefore, it is easy to observe the conductivity of semiconductors and metals.

5. The number of carriers involved in conduction includes electrons and holes. In general, metals have far more carriers than semiconductors, especially conductors of this certificate. Metals are electronically conductive and have low mass and high mobility, whereas semiconductors have low hole mobility.

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.

1. N-type semiconductors.

N-type semi-bent conductors are also known as electronic-type semiconductors.

i.e. free electrons.

Impurity semiconductors with a beam concentration much greater than the hole concentration.

Principle of formation. Both doping and defects can cause conduction bands.

An increase in the concentration of electrons in the medium. For germanium, silicon semiconductor materials.

Doped group elements, when the impurity atoms replace the germanium and silicon atoms in the crystal lattice in a substitution manner, they can provide a covalent bond that satisfies the difference.

An extra electron outside of the coordination, which forms an increase in the concentration of conduction band electrons in the semiconductor.

2. P-type semiconductors.

P-type semiconductors generally refer to hole-type semiconductors, which are mainly positively charged hole-conductive semiconductors.

Formation. P-type semiconductors are formed by adding trivalent elements (such as boron) to pure silicon crystals to replace the position of silicon atoms in the crystal lattice. In p-type semiconductors, holes are many, and free electrons are few, and they mainly rely on holes to conduct electricity. Due to the amount of positive charge in p-type semiconductors.

It is equal to the amount of negative charge, so p-type semiconductors are electrically neutral. Holes are mainly provided by impurity atoms, and free electrons are formed by thermal excitation.

There are two types of conductive semiconductors, which are p-type semiconductors and n-type semiconductors. They differ in the type of conduction by the impurity ions they do.

In semiconductor manufacturing, in order to increase its conductivity, some impurity elements are usually intentionally incorporated into the semiconductor crystal. This method is called doping.

When doped with trivalent elements such as boron, aluminum, etc., they are electron-deficient and have some positive charges, and they will be covalently bonded with the original tetravalent elements in semiconductors such as silicon, germanium, etc., thus forming holes, in semiconductors, holes are equivalent to an electron-deficient position, which can be regarded as a positively charged particle. At this point, semiconductors evolved into p-type semiconductors.

When doped with pentavalent elements such as phosphorus, arsenic, etc., they all have too many electrons, so there will be a few more quiet electrons, and these extra electrons will form covalent bonds with the original tetravalent elements of the semiconductor, such as silicon, germanium, etc., thus forming additional electrons. At this point, semiconductors evolved into n-type semiconductors.

In p-type high-ride semiconductors, the current is mainly contributed by holes; In n-type semiconductors, the current is mainly contributed by foreign free electrons. Among semiconductor devices, p-type semiconductors and n-type semiconductors are important foundations for the realization of various work ideas.

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.

1. The conductivity of semiconductors is between conductors and insulators, silicon germanium, selenium and most metal oxides and sulfides are semiconductors 2. Common semiconductors include thermistors (such as oxides such as drills, nickel, etc.), photoresistors (such as sulfides and selenization of lead) 3. After a trace amount of impurities are incorporated into pure semiconductors, its conductivity can be increased by hundreds of thousands or even millions of times. For example, when pure silicon is doped with 1 part per million of boron, the resistivity of silicon is greatly reduced, and a variety of semiconductor devices such as diodes, bipolar transistors, field-effect transistors and thyristors are made by using this property. 4. Intrinsic semiconductors are completely pure semiconductors with complete lattice.

5. In the crystal structure of intrinsic semiconductors, atoms form a covalent bond structure in the form of shared electron pairs. After gaining a certain amount of energy, the electrons in the covalent bond can break free from the nucleus and become free electrons, leaving a vacancy in the covalent bond family and becoming a hole. Both free electrons and holes are called carriers.

Semiconductors: Objects with electrical conductivity between conductors and insulators (such as germanium, silicon, gallium arsenide, and many metal oxides) have two properties of semiconductors: photosensitive, thermal, and doping.

The conductivity of semiconductors increases with increasing temperature, while the resistance of thermistors with negative temperature characteristics decreases when the temperature increases.

What is the significance of unidirectional conduction of semiconductors? Why do you need it for one-way conduction?

Hello, I am glad to answer for you, the main characteristic of the diode is unidirectional conductivity, that is, under the action of forward voltage, the on-resistance is very small; Whereas, under the action of reverse voltage, the on-resistance is very large or infinite. It is precisely because the diode has the above characteristics that it is often used in the circuit to rectify, the voltage stabilization principle of the voltage regulator diode: the characteristic of the voltage regulator diode is that after the reverse voltage breakdown, the pure voltage of the slip book at both ends of the diode is basically unchanged.

The rectifier diode is damaged after reverse breakdown. In this way, when the voltage regulator tube is connected to the circuit, if the voltage fluctuation of the power supply voltage fluctuates, or other reasons cause the voltage of each point in the circuit to change, the voltage at both ends of the load will remain basically unchanged. Zener diodes are used to regulate voltage or use as a reference voltage in series circuits Rectifier diodes and Zener diodes are both PN semiconductor devices.

The difference is that the rectifier diode uses unidirectional conductivity. Zener diodes take advantage of their reverse characteristics. Reverse connection in the circuit.