Distribution of electrically active nickel atoms in silicon crystals measured by means of deep level transient spectroscopy

Diffusion profiles of electrically active nickel atoms (substitutional nickel atoms; Nis) in dislocated n- and p-type, and dislocation-free n-type silicon crystals are investigated by deep level transient spectroscopy (DLTS). The concentrations of Nis are evaluated from DLTS signals due to amphoteric nickel center which introduces an acceptor level of Ec-0.46eV in n-type silicon and a donor level of Ev+0.18eV in p-type silicon. The profiles are analyzed on the basis of the theory of the dissociative mechanism. It is found that dislocations in dislocated silicon and presumably precipitates of nickel in dislocation-free silicon play the important roles as sinks and sources of vacancies existing in the crystal bulk, giving rise to the flat distribution of Nis.