Question

Pure silicon and germanium are:

• A. conductors
• B. insulators
• C. semiconductors
• D. none of the above

Answer 1

The correct option is C semiconductors

Pure silicon and germanium are semiconductors.
The addition of small amount of foreign impurity in the host crystal is called as doping. It results in an increase in the electrical conductivity of the crystal. Doping of group 14 elements (such as Si, Ge, etc.) with elements of group 15 (such as As) produces an excess of electrons in the crystals, thus, giving n-types semiconductors. Doping of groups 14 elements with group 13 elements (such as Indium) produces holes (electron deficiency) in the crystals. Thus, p-type semiconductors are produced. The symbol 'p' indicates flow of positive charge.