Double-Acceptor Behavior of Zinc in Silicon

Abstract

Zinc has an acceptor level at 0.31 ev from the valence band as noted by Fuller and Morin. Under proper doping conditions, another level is observed at 0.55 ev from the conduction band in $n$-type silicon samples into which zinc has been diffused. Gold, manganese, and iron, however, have levels close to 0.55 ev. Gold is eliminated as an interfering impurity on the basis of neutron activation analysis. Manganese and iron are unlikely to be present in high enough concentrations on the basis of their electrical activity in samples deliberately doped with these elements. Mobility and radioactive solubility studies tend to confirm the hypothesis that the 0.55-ev level represents a second acceptor level associated with zinc.