The addition of trivalent impurity creates large number of holes in the valence band.At room temperature, the number of holes in the valence band is greater than the number of electrons in the conduction band. Hence, the probability of occupation of energy levels by the holes in the valence band is greater than the probability of occupation of energy levels by the electrons in the conduction band. This probability of occupation of energy levels is represented in terms of Fermi level. Therefore, the Fermi level in the p-type semiconductor lies close to the valence band.
It's zero because dopant is neutral and intrinsic semiconductor is also neutral. So neutral plus neutral material gives a neutral material (extrinsic semiconductor)
