What are the main materials of semiconductors?

Semiconductor: The conductive performance at room temperature is between conductor and insulator.

insulator).

Main Materials: Elemental Semiconductors: Germanium and Silicon are the most commonly used elemental semiconductors;

Compound semiconductors: including group and group compounds (gallium arsenide.

gallium phosphide, etc.), group and group compounds (cadmium sulfide, zinc sulfide.

etc.), oxides (oxides of manganese, chromium, iron, copper), and solid solutions consisting of - and - compounds.

gallium-aluminum-arsenic, gallium-arsenic-phosphorus, etc.).

Technical research field:

1) Integrated circuits.

It is one of the most active areas in the development of semiconductor technology and has developed to the stage of large-scale integration. Tens of thousands of transistors can be made on a few square millimeters of silicon wafers, and a micro-information processor can be made on a silicon wafer, or other more complex circuit functions can be completed. The development direction of integrated circuits is to achieve higher integration and micropower consumption, and to enable information processing speed to reach the microsecond level.

2) Microwave devices.

Semiconductor microwave devices include receiving, controlling, and transmitting devices. Receiver devices below the millimeter wave band are widely used. In the centimeter band, the power of transmitting devices has reached several watts, and people are developing new devices and new technologies to obtain greater output power.

3) Optoelectronic devices.

The development of semiconductor luminescence, camera devices, and laser devices has made optoelectronic devices an important field. Their application scope is mainly optical communication, digital display, image reception, optical integration, etc.

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.

What are semiconductors and what are the common materials?

Common semiconductor materials are as follows:

Germanium and silicon are the most commonly used elemental semiconductors; Compound semiconductors include group and group compounds (gallium arsenide, gallium phosphide, etc.), group and 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.

The classification of semiconductors can be divided into integrated circuit devices, discrete devices, optoelectronic semiconductors, logic ICs, analog ICs, memories and other categories according to their manufacturing technology, and generally these will be divided into subcategories. In addition, there are methods to classify by application field, design method, etc., and although they are not commonly used, they are classified by IC, LSI, VLSI (very large LSI), and their size.

In addition, there are methods that can be divided into analog, digital, analog-digital mixture, and function according to the signal they process.

Features and advantages of semiconductor materials

Semiconductor materials are a class of electronic materials with semiconductor properties that are used to make semiconductor devices. The conduction mechanism of commonly used important semiconductors is realized by two types of carriers, electrons and holes, so there are corresponding n-type and p-type. Semiconductor materials usually have a certain band gap, and their electrical properties are easily affected by external conditions (such as light, temperature, etc.).

Materials of different conductive types are prepared by incorporation of specific impurities. Impurities, especially heavy metal fast-diffusing impurities and deep-level impurities, have a particularly strong impact on material properties.

Therefore, semiconductor materials should have high purity, which requires not only that the raw materials used to produce semiconductor materials should have a fairly high purity, but also require an ultra-clean production environment to minimize impurity pollution in the production process. Most semiconductor materials are crystals, and semiconductor devices have high requirements for the crystal integrity of materials. In addition, there are strict requirements for the uniformity of the various electrical parameters of the material.

Monocrystalline silicon will remain the material of choice for the electronics industry for the foreseeable future, but gallium arsenide, a newcomer to the semiconductor family, has rapidly grown into an important semiconductor electronic material second only to silicon. Gallium arsenide plays an important role in the contemporary optoelectronic industry, with 50% of its products used in military and aerospace applications, 30% in communications, and the rest in computers and test instruments.

The special structure of gallium arsenide material gives it attractive properties. According to the principle of quantum mechanics, the smaller the effective mass of an electron, the faster it will move, whereas the effective mass of an electron in gallium arsenide is 1 15 of the mass of a free electron and only 1 3 of a silicon electron. Transistors made of gallium arsenide can switch 1 to 4 times faster than silicon transistors, making it possible to make faster and more powerful computers.

Because of the high speed of electron movement of gallium arsenide, it can be used to prepare microwave devices with a working frequency of up to 1010 Hz, which plays a key role in satellite data transmission, communications, military electronics, etc. In fact, the most important feature of the group semiconductors, represented by gallium arsenide, is its optoelectronic properties, that is, in the case of light or an external electric field, electron excitation releases light energy. Its light emission efficiency is higher than that of other semiconductor materials, and it can be used to make not only light-emitting diodes, photodetectors, but also semiconductor lasers, which are widely used in optical communications, optical computers and space technology, and the development prospects are encouraging.

Like any semiconductor material, gallium arsenide materials are sensitive to impurity elements and must be finely purified. Unlike elemental semiconductors such as silicon and germanium, it also needs to ensure an accurate chemical ratio, otherwise the electrical properties of the material will be affected.

For these reasons, the preparation process of gallium arsenide single crystals is complex and costly. China has used microgravity conditions to grow gallium arsenide single crystals on artificial satellites, and has achieved success. In addition, thin film epitaxial growth technology, which can accurately control the thickness and resistivity of single crystal thin films, has attracted more and more attention in the preparation of semiconductor materials and devices.

In just over a decade, there have been more than 1,000 gallium arsenide products researched and developed in the United States alone. According to the International Conference on GaAs Integrated Circuits in the late 90s, the market sales of GaAs integrated circuits will double every year, forming a scale of billions of dollars. Both gallium arsenide and the family of compound semiconductors it represents, have unique skills that need to be further developed.

Elemental semiconductor materials refer to semiconductor materials that are composed of monomeric elements.

A total of 12 elements have semiconducting properties:

Silicon, germanium, boron, tellurium, iodine, and some allotropes of carbon, phosphorus, arsenic, sulfur, antimony, and tin.

1. N-type semiconductors.

N-type semiconductors are also known as electron-type semiconductors, i.e., impurity semiconductors with a concentration of free electrons much greater than the concentration of holes.

Principle of formation. Both doping and defects can lead to an increase in the concentration of electrons in the conduction band. For germanium and silicon semiconductor materials, doped with group elements, when the impurity atom replaces the germanium and silicon atoms in the crystal lattice in an alternate way, it can provide a superfluous electron in addition to satisfying the covalent bond coordination, which forms an increase in the concentration of conduction band electrons in the semiconductor, and the impurity atom is called the donor.

The donors of group compound semiconductors tend to use OR group elements. Some oxide semiconductors, their chemical ratio often presents hypoxia, these oxygen vacancies can show the role of donor, so this type of oxide is usually electronically conductive, that is, n-type semiconductors, vacuum heating, can further enhance the degree of hypoxia.

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.

Since the amount of positive charge and the amount of negative charge in p-type semiconductors are equal, p-type semiconductors are electrically neutral. Holes are mainly provided by impurity atoms, and free electrons are formed by thermal excitation.

Features: (1) N-type semiconductors.

Since the amount of positive charge and the amount of negative charge in n-type semiconductors are equal, n-type semiconductors are electrically neutral. Free electrons are mainly provided by impurity atoms, and holes are formed by thermal excitation. The more impurities are incorporated, the higher the concentration of polysomes (free electrons) and the stronger the conductivity.

2. P-type semiconductors.

The more impurities are incorporated, the higher the concentration of polysons (holes) and the stronger the conductivity.

Semiconductors are materials that have electrical conductivity between conductors and insulators at room temperature.

Semiconductors are used in integrated circuits, consumer electronics, communication systems, photovoltaic power generation, lighting, high-power power conversion and other fields, such as diodes are devices made of semiconductors.

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.

Common semiconductor materials are silicon, germanium, gallium arsenide, etc., and silicon is the most influential one in various semiconductor material applications.

Semiconductor materials include carbon, silicon, arsenic, phosphorus, boron, etc.

Semiconductor materials include silicon, germanium, gallium arsenide, etc.

Substances and materials in nature can be divided into three categories: conductors, semiconductors and insulators according to their conductivity. In general, the conductivity of semiconductors decreases with the increase of temperature, and all buried materials with the above two characteristics can be classified into the scope of semiconductor materials, but the internal basic properties of semiconductors are leaked by various external factors such as light, heat, magnetism, electricity, etc.

Physical effects and phenomena caused by the action of semiconductors, which can be collectively referred to as the semiconductor properties of semiconductor materials. The vast majority of the matrix materials that make up solid-state electronic devices are semiconductors, and it is the various semiconductor properties of these semiconductor materials that give different types of semiconductor devices different functions and characteristics, and the basic chemical characteristics of semiconductors are the existence of saturated covalent bonds between atoms.

Practical application:

All semiconductor materials need to be purified from raw materials, and the purity required is more than 6 9's and up to 11 9's. There are two types of purification methods, one is purification without changing the chemical composition of the material, which is called physical purification. The other type is to turn the elements into compounds for purification, and then reduce the purified compounds into elements, which is called chemical purification.

The methods of physical purification include vacuum evaporation, regional refining, crystal pulling purification, etc., and the most used is regional refining. The main methods of chemical purification are electrolysis, complexation, extraction, rectification, etc., and the most used is distillation. Because each method has certain limitations, a process combining several purification methods is often used to obtain qualified jujube waste.

The above content reference: Encyclopedia - Semiconductor.