Semiconductors can be made of a single material or a combination of several different materials. In early semiconductor devices germanium was often used. However in today's semiconductor industry, silicon is commonly used.

Silicon is very easy to find in Nature. Ordinary sand, like on the beach or in the desert for example, is nothing more than one silicon atom combined with two oxygen atoms. However, if you want silicon in its pure form suitable for the production of, for instance, computer chips it has to be purified in a carefully monitored process.

One of the main reasons for the popularity of silicon is that it is stable and can be heated to a rather high degree without loosing its material characteristics. This means that engineers can be sure it will perform according to their plans, even under quite extreme conditions.

Just to make sure we avoid misunderstandings, when we talk about silicon, we don't mean silicone spelled with an "e" at the end, 'cause that is a material mostly known for its use in human implants.

To understand the principles of semiconductors, it is good to first understand the basics of atoms and energy levels within atoms. So that's where we're going to start.