IN n-TYPE SEMICONDUCTOR.

• At 0K the fermi level E_{Fn} lies between the conduction band and the donor level.
• As temperature increases more and more electrons shift to the conduction band leaving behind equal number of holes in the valence band. These electron hole pairs are intrinsic carriers.
• With the increase in temperature the intrinsic carriers dominate the donors.
• To maintain the balance of the carrier density on both sides the fermi level $E_{Fn}$ gradually shifts downwards.
• Finally at high temperature when the donor density is almost negligible E_Fn is very close to$ E_{Fi}$.

IN p-TYPE SEMICONDUCTOR.

• At 0K the fermi level $E_{Fp}$ in a p-type semiconductor lies between the acceptor level and the valence band.
• With the increase in temperature more and more holes are created in the valence band as equal number of electrons move to the conduction band.
• As temperature increases the intrinsic holes dominate the acceptor holes.
• Hence the number of intrinsic carriers in the conduction band and in the valence band become nearly equal at high temperature.
• The fermi level $E_{Fp}$ gradually shifts upwards to maintain the balance of carrier density above and below it.
• At high temperature when the acceptor density become insignificant as compared to the intrinsic density, $E_{Fp}$ is positioned very close to the intrinsic fermi level $E_{Fi}$ but little below it.