Chemical trends for deep levels associated with vacancy-impurity complexes in semiconductors

A theory of the deep levels produced by triplet vacancy-impurity complexes in covalent semiconductors is presented. The major chemical trends in the deep levels of a1 and b1 symmetry are predicted for such complexes in 10 materials. These calculations show that a triplet vacancy-impurity complex can produce deep levels at energies where neither the corresponding vacancy-impurity pair nor the isolated impurity produce any.