This Demonstration shows the charge carrier concentration in silicon (Si) and doped Si (n- and p-types) as a function of temperature and dopant concentration. The corresponding electron band configurations are shown to the right of the plot. Phosphorous doping creates n-type Si, while boron doping creates p-type Si.

where is the effective density of states (), is the energy gap (eV), is Boltzmann's constant (eV/K), is temperature (K), and is the effective density of states at 300 K.

The carrier concentration for pure silicon () is:

.

The carrier concentration for doped silicon () is:

,

where is the atomic concentration of dopant atoms, is the activation energy for the electron of a dopant atom, and is the ideal gas constant.