An n-type semiconductor is made by adding a small amount of a Group-V element such as phosphorous (P) or arsenic (As) to the intrinsic semiconductor. Group-V elements have five valence electrons per atom.

A p-type semiconductor is made by doping an intrinsic semiconductor with Group-III elements such as boron (B) or aluminium (Al). In these elements, there are only three valence electrons per atom.

Intrinsic semiconductors are elements with four valence electrons per atom, i.e. elements that occur in “Group-IV” of the periodic table such as silicon (Si) and germanium (Ge).

A doped semiconductor is referred to as an extrinsic semiconductor.

2)The terms n- and p-type doped do only refer to the majority charge carriers. Each positive or negative charge carrier belongs to a fixed negative or positive charged dopant.

p and n type materials are NOT positively and negatively charged.

An n-type material by itself has mainly negative charge carriers (electrons) which are able to move freely, but it is still neutral because the fixed donor atoms, having donated electrons, are positive.

Similarly p-type material by itself has mainly positive charge carrier (holes) which are able to move relatively freely, but it is still neutral because the fixed acceptor atoms, having accepted electrons, are negative.