A Guide to Physics Problems. Part 2. Thermodynamics, Statistical Physics, and Quantum Mechanics

236 SOLUTIONS

4.104 Electrons and Holes (Boston, Moscow

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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