To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like

Options

A. A conductor
B. An `N` -type semiconductor
C. a `p`-type semiconductor
D. An insulator

Answer

C

Explanation

When gallium is added to germanium all of the three valence electrons from covalent bonds with one each valence electron of three nearest germanium atom while the valence electron of the fourth nearest germanium atom is not able to from bond. Thus, there is a deficiency of one electron. This is called hole. Such an impure germanium crystal is called `p`-type semiconductor