Semiconductors are the divided class of matters. At first that unique class 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. The first successful research was carried out by the Russian physicists in 1923. They proved that semiconductors may be used to accelerate fluctuations. There was no possibility to develop some sophisticated devices as igbt modules. First transistor was created in Bell's laboratory in 1949. This event impacted on the fast development of semiconductor devices. That was the start of the epoch of semiconductor technologies.
The interest to optical characteristics of semiconductors revived due to research of induced emission in semiconductors. It caused the appearing of semiconductor laser device based on usage of p - n barriers and then on heterojunction.