The origin of the I1d excitonic emission in ZnSe

An investigation employing nuclear transmutation to probe the effects of copper doping in ZnSe is presented. Three experimental observations are reported in this investigation. With the first, as-grown ZnSe is irradiated with thermal neutrons which results, after thermal annealing, in the incorporation of Cu_Zn centers. Results are consistent with isolated Cu_Zn being involved in the copper-red and copper-green emissions in ZnSe but not in the I₁ ^d excitonic emission. Next are annealing experiments of as-grown wafers of ZnSe which are thermally annealed in a zinc-rich atmosphere. After annealing, the wafers show a remarkable reduction in the I₁^d emission. Finally, we report observations of homoepitaxial layers of ZnSe grown from elemental zinc and selenium. In these experiments, we have seen that the I₁^d can be greatly reduced, often eliminated, by growing the layers in a zinc-rich atmosphere. All three observations are consistent with the I ₁^d emission being associated with V_Zn but not with Cu_Zn centers,