As soon as the electricity studies begin it has to be learned at once what is the concept of the electrical resistance, that is to say this difficulty that there put up all the bodies to be crossed by the electric current. This way bodies as the copper, the silver, the tungsten, etc., have a very low resistividad. These materials are called good materials.
On the contrary there exist other bodies that offer a high resistance to allow to cross for the electric current, like the glass, the plastic, the bakelite, etc.
In a place between these two cases are the material semiconductors. The most well-known and used there are the germanium (Ge) and the silicon (If), the materials that are made by Ge or If they will give 50 times more resistance than the drivers, but to his you see and more insulators than those who are not drivers. Then the semiconductors are bad drivers, but at the same time they are insulating villains.
