N-Type P-Type Semiconductor

The addition of a small percentage of foreign atoms in the regular crystal lattice of silicon or germanium produces dramatic changes in their electrical properties, producing n-type and p-type semiconductors.

Pentavalent impurities

(5 valence electrons) produce n-type semiconductors by contributing extra electrons.

Trivalent impurities

(3 valence electrons) produce p-type semiconductors by producing a "hole" or electron deficiency.

N-Type Semiconductor :

The addition of pentavalent impurities such as antimony, arsenic or phosphorous contributes free electrons, greatly increasing the conductivity of the intrinsic semiconductor. Phosphorous may be added by diffusion of phosphine gas (PH3).

P-Type Semiconductor :

The addition of trivalent impurities such as boron, aluminum or gallium to an intrinsic semiconductor creates deficiencies of valence electrons,called "holes". It is typical to use B2H6 diborane gas to diffuse boron into the silicon material.