Introduction to semiconductors in the circuit board industry: the almost perfect semi-insulating semiconductor materials

1. Semiconductor Definition :

Semiconductor is a material that refers to a material whose electrical conductivity is between that of a conductor and an insulator at room temperature. Semiconductors play a pivotal role in all electronics manufacturing industries. For example, a diode is a device made of semiconductors. The conductivity of a semiconductor can vary from completely non-conducting to completely conducting, depending on the external conditions it is exposed to. So, it can be used to make electronic components with different states. Whether it is science and technology, economical or practical value, semiconductors are a handful of good materials. Among semiconductor materials such as silicon silicon semiconductor, germanium semiconductor, and gallium arsenide semiconductor, silicon semiconductor is the most widely used in electronic manufacturing, and it is also the most commonly used semiconductor material in business. Compared with insulators and conductors, semiconductors have a relatively short history. According to materials, semiconductor materials were only recognized by academia in the 1930s and truly entered life.

Since it is an introduction to semiconductors, I have to introduce a proper term "intrinsic semiconductor" for a long time. Intrinsic semiconductors are simply semiconductors that do not contain any impurities or lattice defects. However, due to the relatively large resistivity of intrinsic semiconductors, they have little practical value, so they are not used commercially.

2. Semiconductor classification:

We know that there are more materials for insulators and conductors, so there will be no shortage of semiconductor materials. Semiconductor materials are generally classified according to chemical composition, one is elemental semiconductor, and the other is compound semiconductor. The most commonly used elemental semiconductors are germanium semiconductors and counter semiconductors; compound semiconductors are more commonly used, such as gallium arsenide semiconductors, gallium phosphide semiconductors, cadmium sulfide semiconductors, and so on.

3. Semiconductor history:

The discovery of semiconductors can be traced back to 1833, when Faraday in England discovered sulfide Silver, which reduces its own resistance as temperature increases. This is the first time a semiconductor phenomenon has been discovered. Later, in 1839, Berclair of France discovered a phenomenon, that is, under the care of the son, the junction formed by the contact between the semiconductor and the electrolyte can generate a voltage. This phenomenon is now known as the photovoltaic effect. In 1873, another British scientist, Smith, discovered another characteristic of semiconductors - the photoconductive effect. The detailed development process is not listed one by one. However, there is a doubt, that is, why did the definition of semiconductor take so long to be recognized by the academic community? The details of this question also need to read the material "The coming of Materials Science".

4. Five characteristics of semiconductor:

Semiconductor with doping, thermal sensitivity, photosensitivity, negative resistivity temperature characteristics and rectification Features Five features.

5. Application of semiconductors in integrated circuits:

The basis of the integrated circuit is the transistor, and the basis of the transistor is the semiconductor, Therefore, the basis of integrated circuits is semiconductors. Among them, the most common and most widely used semiconductor is silicon semiconductor. So why is silicon semiconductor the darling of integrated circuits? We can consider a few points.

The first point: Anyone who knows chemistry knows that the four most abundant elements on the earth are oxygen, silicon, aluminum and iron. According to this order, we know that silicon is the second most abundant element on the earth. The most abundant content in the earth's crust is silicon, which means that the cost of extracting silicon semiconductor raw materials is low.

Second point: It is easy to manually control the impurity concentration in silicon semiconductors, and it is more convenient to obtain components that meet the requirements, that is, transistors. And the silicon on its surface is oxidized to form a very stable oxide film silicon dioxide to act as an insulating film.

The third point: In terms of technology, silicon semiconductors are relatively easy to implement processes such as oxidation and lithography. And the controllability of its performance is higher than that of other types of semiconductors.