Semiconductors are believed to be a special class of chemical elements. Scientists got known about these substances in the end of the 19th century, but just in the 20th century scientists managed to get more knowledge about them. The first successful experiment was carried out by the Russian scientists in 1923. They proved that semiconductors can be utilized to accelerate fluctuations. During further years diodes were ejected by tubes. The most considerable event in the history of semiconductor devices was the creation of the first transistor by Bell corporation in 1949. Since then many people all over the world become interested in such type of substance as semiconductors.

Many physicists carry out a great deal of researches just to gain more knowledge about such characteristic of semiconductors as stimulated emission. By means of such principles as p - n barriers and heterojunction physicists managed to create laser device in the beginning of the 60's.

Today we may see a great deal of various pulsed power devices that operate with assistance of usage of semiconductors. Today it is impossible to carry out any experiments without some new technologies that are based on usage of semiconductors.

The main reason why semiconductors are believed to be the divided kind is that they have got a conductivity which is between the conductivities of metals and isolators. 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 who decided to get more knowledge about semiconductors was Abram Ioffe - Russian scientist. He found that semiconductors are the special type of crystals with some definite features. There are electron conduction and hole conduction provided by semiconductor devices. It is dependant on the chemical mixture of the used admixtures. For instance, by usage of some admixtures the value of electron conduction may be changed.

The most significant semiconductor devices which are utilized in technologies are diodes, transistors and thyristors that are founded on materials with electron and hole conductions. Semiconductors are widely utilized as their characteristics are useful for almost every electronic system. They are able to turn luminous and heat energy into electricity and vice versa. Some of them are even able to develop cold and heat. Semiconductors perform the basic functions in lots of different devices: atomic batteries, quantum generators, processors and even primitive radio receivers. Almost every worker that works in organization related to electricity ought to know how important the voltage sensors are. If we compare devices operating on semiconductors and tube systems we will see that semiconductors are significantly smaller and lighter. The analogue systems are not equal if we speak about their reliability and power. Tube falls behind.

From day to day we can hear about some modern systems which assist people to have more conveniences or even save the life.