There is a detached type of substances which is called semiconductors. In the first time that unique class was discovered in the 1890's but more completely it started to be discovered just after the First World War in Europe and in Soviet Union. In 1923 Russian scientists proved the ability of utilizing of semiconductor-metal contacts to quicken the generation of fluctuations. There was no opportunity to create some sophisticated devices as diodes. Only in the beginning of the 60's with the appearing of transistors in 1949 the wide usage of crystal detectors started. That was the beginning of the era of semiconductor technologies.

Stimulated emission is really a very interesting characteristic of semiconductors that has been discovered for several tens of years. By usage of such principles as p - n barriers and heterojunction scientists managed to create laser system in the beginning of the 60's.

Modern developers can propose a wide range of different semiconductor devices to their consumers, for instance pulsed power devices. If there were no semiconductor devices utilized in modern technologies, we won't have a possibility to carry out such great experiments which are important for other sciences.

Semiconductors are a wide class of substances which are characterized by the value of conductivity that is situated between the conductivities of metals and isolators. There are several substances that are basically used to create the semiconductor devices. They are germanium, selenium, silicon, etc.

Scientists haven't been interested in semiconductors for quite a long period of time. Abram Ioffe is a Russian physicist who started carrying out different experiments in field of semiconductors. This genius proposed many techniques of use of semiconductors and every up to date system is based on these principles. Every semiconductor device has got such basic features as electron and hole conduction. Such features may be modified by usage of adding some admixtures or changing temperature. The admixtures affect significantly on the electron conduction of the semiconductors.

The most significant semiconductor systems that are utilized in technologies are diodes, transistors and thyristors which are founded on materials with electron and hole conductions. Their unique characteristics are frequently used today, but they became widespread only ten years ago. There are systems based on semiconductors that can convert light and heat energy into electric power and vice versa. With usage of electric power they can create heat and cold. Semiconductor devices can be used in radio receiver and quantum generator, in little atomic battery and in microprocessors. Such systems as current sensors are commonly used in any construction related to the electricity. The mass and overall dimensions of semiconductor systems are significantly smaller than their tube analogues. The analogue devices are not equal in case we speak about their reliability and power. Tube drops behind.

There are many various devices nowadays, which considerably facilitate our life and all these inventions appear only thanks to the semiconductor systems.