Thus, in intrinsic semiconductors, both electrons and holes contribute to conduction, and their “number” (density) is equal.

The true magic of semiconductors lies in doping, a process where small, controlled amounts of impurities are added to the pure semiconductor material. This process dramatically alters the effective “number of electrons” (and holes) available for conduction, creating two main types of extrinsic semiconductors:

Ntype Negative type Semiconductors

Doping with elements that have one more valence electron than the semiconductor (e.g., Phosphorus in Silicon). These “donor” impurities readily give up their extra electron into the conduction band, significantly increasing the “number of electrons” available for conduction. Electrons become the majority charge carriers.
P-type (Positive-type) Semiconductors: Doping with elements that have one less valence electron than the semiconductor (e.g., Boron in Silicon). These “acceptor” impurities create an excess of holes, as they readily “accept” an electron from a neighboring bond. Holes become the majority charge carriers.
By precisely controlling the type and concentration of the dopant, manufacturers can fine-tune the “number of electrons” (and holes) available, thereby controlling the conductivity of the material. This controllable conductivity is what allows for the creation of diodes, transistors, and integrated circuits, which are the fundamental building blocks of all electronic devices. The ability to switch between high and low conductivity by manipulating the charge carriers is what makes semiconductors indispensable.

The inherent conductivity of pure

Semiconductors, while useful, is too limited for practical electronic applications. The true revolution came with the advent of doping, a precise process that involves adding tiny amounts of specific impurities to a pure semiconductor material. Doping fundamentally manipulates the “number of electrons” (and holes) available for conduction, creating materials with vastly enhanced and controllable electrical properties.