The 1-fF(E) increases in the Valence band for n-type semiconductors.

Explanation:
In a semiconductor material, the valence band is the highest energy band that is completely filled with electrons at absolute zero temperature. The conduction band, on the other hand, is the next higher energy band that is empty or partially filled with electrons.

For n-type semiconductors, the material is doped with impurities that introduce extra electrons into the crystal lattice. These impurities are called donor impurities. The donor impurities have more valence electrons than the atoms in the semiconductor crystal, and these extra electrons become delocalized and contribute to the conduction of electricity.

When an external electric field is applied to the n-type semiconductor, the electrons in the valence band gain energy and can transition to higher energy levels in the conduction band. The probability of an electron occupying a particular energy level in the conduction band is given by the Fermi-Dirac distribution function, denoted as f(E).

The 1-fF(E) term in the distribution function represents the probability of the energy level being unoccupied, or the probability of finding a hole in that energy level. In the case of n-type semiconductors, the valence band is full of electrons, and the conduction band is partially filled. Therefore, the 1-fF(E) term will be significant in the valence band, where there is a high probability of finding an unoccupied energy level (hole).

In summary, the 1-fF(E) term increases in the valence band for n-type semiconductors because the valence band is filled with electrons and has a high probability of having unoccupied energy levels (holes).