Deep levels of copper in silicon

Defect impurity levels have been examined in copper-diffused p-and n-type silicon using deep level transient spectroscopy. Levels at Ev+0.09, Ev+0.23, and Ev+0.42 eV have been observed in both types of material, although the deeper levels were only oberved in n-type material after post-diffusion annealing at 200 °C. Associated with the appearance of these levels in n-type material was another level at Ec−0.16 eV. This may be a further charge state of the center responsible for the Ev+0.23 eV and Ev+0.42 eV levels or the two centers may be decomposition products of a thermally unstable complex. Luminescence measurements have revealed the previously reported Cu-Cu spectrum in all the copper-diffused samples. The occurrence of this signal could not be correlated with the presence of the levels at Ev+0.23, Ev+0.42, or Ec−0.16 eV; this leaves the center at Ev+0.09 eV as the likely origin of the signal.