The electrical behavior of 20–50‐keV Bi implanted layers in silicon has been evaluated using Hall effect and sheet resistivity measurements. Implants of greater than 1014/cm2performed at room temperature show a large increase in the number of carriers/cm2for short anneals at ≈600°C that is associated with the reordering of the lattice. Although Rutherford scattering measurements (performed at Chalk River Nuclear Laboratories) indicate that ≈80% of the Bi atoms are substitutional, only ≈20% are effective electrically. The peak value of the carrier density distribution is ten times the corresponding maximum solid solubility.