Cadmium–lithium defects in silicon

Three photoluminescence (PL) bands, observed for silicon samples doped with Cd and quenched from high temperatures, have relative intensities which depend strongly on the annealing history of the samples. The intensity of two of the bands is enhanced by deliberate diffusion of Li into Si:Cd. Isotope substitution experiments show that all three PL centres contain one Cd atom and that there are two Li atoms in at least one of the defects. Zeeman measurements show the excited state manifolds consist of both singlet and triplet states for the three centres, with isotropic triplet state g values close to 2.