Quasi-conductor are the detached class of substances. At first this unique type was discovered in the 1890's but more thoroughly 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 usage of semiconductor-metal contacts to accelerate the generation of fluctuations. There was no possibility to develop some unique devices as semiconductor assembly. The most considerable event in the history of semiconductor devices was the creation of the first transistor by Bell corporation in 1949. The intense studying of the characteristics of semiconductors was started at the same time.

A lot of scientists carry out a huge amount of experiments just to gain more knowledge about such feature 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.

Modern developers can propose a wide spectrum of variant semiconductor devices to their consumers, for instance power semiconductor devices. If there were no semiconductor devices used in the newest technologies, we won't have an opportunity to carry out such great experiments which are significant for other sciences.

Semiconductors are a broad kind of matters that are characterized by the value of conductivity that is situated between the conductivities of metals and isolators. There are some elements that are basically utilized to develop the semiconductor devices. They are germanium, selenium, silicon, etc.

It sounds a little strange but scientists didn't want to perform researches of semiconductors for a long time. The first experiments of semiconductors were started by famous Russian scientist Abram Ioffe. He found that this wonderful type of matter has got some special characteristics and determined how they can be used. There are electron conduction and hole conduction developed by semiconductor devices. The features of semiconductor are dependant on the conditions they are placed. The admixtures affect considerably on the electron conduction of the semiconductors.

Almost every area of newest technologies means usage of semiconductors. Diodes, transistors and thyristors are the most frequently used systems. Semiconductors are widely utilized as their characteristics are useful for almost every electric device. They are able to turn light and heat energy into electric energy and vice versa. Several of them are even able to develop cold and heat. Such devices as radio receivers, atomic batteries, quantum generator, microprocessors etc comprise semiconductors. Workers can't do without semiconductor rectifiers, changers, disconnectors and amplifiers. The mass and overall dimensions of semiconductor devices are considerably smaller than their tube variants. When semiconductors are used some important features as power and reliability are being developed a lot.

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