Germanium and silicon behave as semiconductor only when doped with some group 15 elements like P or As.
Semiconductors materials such as silicon (Si), germanium (Ge) and gallium arsenide (GaAs) have electrical properties somewhere in the middle, between those of a conductor and an insulator. Silicon and Germanium are classed as intrinsic semiconductors in that they are chemically pure, containing nothing but semi-conductive material. But by controlling the number of impurities added to this intrinsic semiconductor material, it is possible to control its conductivity.
- The process of adding donor or acceptor atoms to semiconductor atoms (the order of 1 impurity atom per 10 million (or more) atoms of the semiconductor) is called Doping.
- Antimony (symbol Sb) and phosphorus (symbol P) are frequently used as a pentavalent additive to silicon.