When the impurity atom is a trivalent atom say indium, boron or aluminium, these atoms will replace the silicon atom as shown.
The 3 valence electrons of Indium atom bond covalently with 3 of silicon atom. There is one incomplete covalent bond due to deficiency of an electron. This bond can be completed if one of Si-Si bond is broken and that electron fills this vacancy, but a hole is created in Si-Si bond. Therefore the holes move in the semiconductor structure and the conductivity here is mainly due to motion of holes or positive charge. Such semiconductors are therefore called P type semiconductors.
As temperature increases, some bonds may get ruptured and release equal electrons and holes but the total number of electrons is relatively small than holes. Hence in P type, holes are majority charge carriers and electrons are minority charge carriers.
