An intrinsic semiconductor with mass of a hole m,, and mass of an electron m, is at a finite temperature T. If the energy of top of the valence band is E, and the energy of bottom of the conduction band is E the Fermi energy of the semiconductor is O E = EF EF kT 3 Er = ( 2 ) + (E + Ec) In 4 = E + Ec 2 = E + Ec 2 kT 2 3 -k&T In 4 m m -kT ln m (Ep + Ec) In mh m m m