Semiconductors are the detached type of matters. 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. In 1923 Russian scientists proved the ability of usage of semiconductor-metal contacts to quicken the generation of fluctuations. There was no possibility to create some unique devices as diodes. First transistor was developed in Bell's laboratory in 1949. That event influenced the quick improvement of semiconductor devices. The intensive research of the features of semiconductors was begun at the same time.

A lot of scientists perform a huge amount of researches just to gain more knowledge about such characteristic of semiconductors as stimulated radiation. First laser system was developed with usage of semiconductors. The first variant was based on p - n barriers, the latest ones - on heterojunction.

Today's producers may offer a wide range of variant semiconductor devices to their consumers, for example asymmetric GTO thyristors. Today it is impossible to perform any researches without some modern technologies that are based on use of semiconductors.

The main reason why semiconductors are considered to be the divided kind is that they have got a conductivity that is between the conductivities of metals and isolators. There are some substances which are mainly used to create the semiconductor devices. They are germanium, selenium, silicon, etc.

It sounds a bit strange but scientists didn't want to perform researches of semiconductors for a long time. Abram Ioffe is a soviet physicist that started carrying out different researches in area of semiconductors. That genius offered many methods of use of semiconductors and every up to date device is based on these principles. There are electron conduction and hole conduction provided by semiconductor systems. These characteristics can be changed by means of adding some admixtures or changing temperature. For instance, by usage of some admixtures the value of electron conduction can be changed.

Almost every sphere of newest technologies implies use of semiconductors. Diodes, transistors and thyristors are the most frequently utilized devices. Their unique features are frequently utilized nowadays, but they became widespread just ten years ago. There are devices based on semiconductors that may convert luminous and heat energy into electricity and vice versa. Heat and cold can be developed by some types of semiconductors. Semiconductor devices can be found in radio receiver and quantum generator, in little atomic battery and in microprocessors. Such systems as fuses are commonly utilized in any construction connected to the electricity. The weight and overall dimensions of semiconductor systems are significantly smaller than their tube analogues. When semiconductors are used some significant characteristics as power and reliability are being improved much.

We can't imagine how the humankind can exist without a lot of devices which are based on usage of semiconductors.