236 SOLUTIONS
4.104 Electrons and Holes (Boston, Moscow
Phys-Tech)
a) Let the zero of energybe the bottom of the conduction band, so
(seeFigureS.4.104). Thenumber ofelectrons may befound from
where for electrons, and the Fermi distribution formula has been
approximated by
The concentration of electrons isthen
where
b) Inan intrinsicsemiconductor