Why p-type&n-type semiconductor are neutral?
Consider first the intrinsic material–no donors. You agree that is neutral. Now we add a donor material. Each atom of donor material is added whole, protons and electrons and is also neutral. So adding donor atoms does not change the neutrality of the material. However, the donor atoms do not “fit right” into the lattice of atoms of the receptor material, making it easier for electrons (in “n” material) or holes (electron absence in “p” material) to “break free” of the forces binding them to the atom. These electrons and holes provide the conductivity of the doped material. The phrase you indicated is poorly written. There is no excess of electrons in n material or lack of electrons in p material. It is just that it takes less energy to free electrons from the forces (covalent bonds) that keep them tied to atoms. At high enough temperature (heat energy) some of these are completely free from the bonds and can flow freely if an electric field is applied. It is not correct to consider t
