4 n-type extrinsic semiconductor

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The semiconductor has been doped with 10^15 (1/cm^3) of donors with a binding energy of 0.05 eV. You get a somewhat different perspective by shifting to a T instead of 1/T plot, or a linear instead of log plot. Switch from 1/T to T to get a sense of the large range of temperatures over which the electron concentration remains constant. (Why then is the chemical potential continually varying in this regime?)

Change the bandgap to 1.1 eV (silicon) to see the effect on the temperature of the extrinsic/intrinsic transition. What happens to the transition temperature if the donor concentration is changed by a factor of ten?

Zoom into the low temperature region to see the "carrier freezeout", the trapping of the carriers by the donors. See if you can understand the temperature dependence of the chemical potential as well as of the carrier concentration. How does the freezeout temperature of around 90 K compare with the donor binding energy? Why are they so different? (0.05 eV corresponds to a temperature of 600 K!)