There is a divided type of matters that is called quasi-conductors. At first this unique class was discovered in the 1890's but more completely it began to be researched only after the First World War in Europe and in Soviet Union. Russian scientists carried out lots of researches. The results showed that semiconductors may help to accelerate the fluctuations and maintain them. There was no opportunity to develop some unique devices as diodes. Just in the beginning of the 60's with the appearing of transistors in 1949 the wide use of crystal detectors started. Since then many people all over the world become interested in such type of matter as semiconductors.

Many physicists perform a huge amount of experiments just to gain more knowledge about such characteristic of semiconductors as stimulated radiation. It led to the appearing of semiconductor laser device based on usage of p - n barriers and then on heterojunction.

Modern producers can propose a broad spectrum of different semiconductor devices to their consumers, for instance diodes. If there were no semiconductor systems used in modern technologies, we won't have an opportunity to perform such great researches which are significant for other sciences.

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

For very long period of time semiconductors haven't got the attention of physicists and engineers. Abram Ioffe is a soviet scientist who began performing different researches in field of semiconductors. This genius proposed many methods of usage of semiconductors and every modern system is based on these principles. There are electron conduction and hole conduction provided by semiconductor devices. Such features may be changed by usage of adding some admixtures or changing temperature. To get the features which are needed for the experiment or proper use of device some admixtures are added to semiconductors.

The most significant semiconductor devices which are used in technologies are diodes, transistors and thyristors that are based on elements with electron and hole conductions. Semiconductors are broadly utilized as their features are useful for almost every electronic device. 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. Such devices as radio receivers, atomic batteries, quantum generator, microprocessors etc comprise semiconductors. Such devices as disconnectors are commonly utilized in any construction connected to the electricity. In case we compare devices equipped with semiconductors and tube systems we will see that semiconductors are significantly smaller and lighter. When semiconductors are utilized some significant features as power and reliability are being developed a lot.

We can't imagine how the humankind can exist without lots of devices which are based on utilizing of semiconductors.