Electron Mobility - Doping Concentration Dependence in Heavily-doped Silicon

Doping Concentration Dependence in Heavily-doped Silicon

The charge carriers in semiconductors are electrons and holes. Their numbers are controlled by the concentrations of impurity elements, i.e. doping concentration. Thus doping concentration has great influence on carrier mobility.

While there is considerable scatter in the experimental data, for noncompensated material (no counter doping) for heavily doped substrates (i.e. and up), the mobility in silicon is often characterized by the empirical relationship:

where N is the doping concentration (either N_D or N_A), and N_ref and α are fitting parameters. At room temperature, the above equation becomes:

Majority carriers:

Minority carriers:

These equations apply only to silicon, and only under low field.