Doping
The intentional insertion of trace impurity atoms into an intrinsic semiconductor lattice to drastically modulate its electrical conductivity and charge carrier density.
Governing formula
N_D (Donors) or N_A (Acceptors) ~ 10¹⁴ to 10¹⁹ cm⁻³
SI unit
Atoms/cm³ (Dopant Concentration)
In depth
Doping replaces semiconductor host atoms with impurity atoms possessing a different valence electron count. Group-15 donors (like Phosphorus in Silicon) add excess free electrons (n-type), while Group-13 acceptors (like Boron) create excess holes (p-type).
Examples in the real world
Doping pure silicon with 1 part per million phosphorus to increase its electrical conductivity by a factor of 10,000.