There is a divided type of substances that is named semiconductors. People got known about these materials in the end of the 19th century, but just in the 20th century scientists managed to obtain more knowledge about them. The first successful research was performed by the Russian scientists in 1923. They proved that semiconductors can be utilized to generate fluctuations. There was no possibility to develop some sophisticated devices as diodes. Only in the beginning of the 50's with the appearing of transistors in 1949 the wide usage of crystal detectors began. That was the start of the era of semiconductor technologies.

The interest to optical features of semiconductors revived due to discovery of simulated emission in semiconductors. It caused the creation of semiconductor laser system based on utilizing of p - n barriers and then on heterojunction.

Nowadays we may see a huge amount of different pulsed power devices that work with help of use of semiconductors. Today it is impossible to carry out any experiments without some modern technologies which are based on use of semiconductors.

The conductivity of semiconductors lies in diapason between conductivity of metals and conductivity of isolators. That characteristic is caused the division of semiconductors as a divided class. Such matters as germanium, silicon, selenium and several others are considered to be semiconductors.

Physicists haven't been interested in semiconductors for very long period of time. The first person that decided to get more knowledge about semiconductors was Abram Ioffe - Russian scientist. He found that this amazing type of substance has some special characteristics and described how they can be used. There are electron conduction and hole conduction developed by semiconductor devices. It is related to the chemical composition of the used admixtures. The admixtures influence considerably on the electron conduction of the semiconductors.

The most important semiconductor systems which are utilized in technologies are diodes, transistors and thyristors that are based on elements with electron and hole conductions. Their sophisticated features are frequently utilized nowadays, but they became spread just ten years ago. They are used to turn luminous and heat energy into electric energy and vice versa. Heat and cold can be produced by some types of semiconductors. Semiconductor devices can be used in radio receiver and quantum generator, in little atomic battery and in microprocessors. Almost every engineer that works in company related to electricity should know how significant the fuses are. The weight and size of semiconductor systems are considerably smaller than their tube analogues. When semiconductors are utilized some significant characteristics as power and reliability are being improved much.

We can't imagine how the humankind may do without lots of devices that are based on utilizing of semiconductors.