Strain-induced level in copper-doped silicon

It has been found that in copper-doped silicon, both the concentration and the degeneracy ratio of the deep acceptor level lying at 0.16 eV from the conduction band edge vary having a maximum and minimum value with increase in copper-doping level. Since the variations of these deep-level parameters correspond very well to that of the silicon crystal lattice strain due to numerous copper precipitates, we can infer that the acceptor level is a strain-induced level which is introduced by copper diffusion.