Deep energy levels in power diodes introduced by iridium diffusion

In our experiments we focused on the origin of deep levels due to Ir diffusion and the influence of Ir diffusion on carrier lifetime and on the electrical characteristics of power diodes. Energy levels associated with iridium diffusion into N-type silicon at energies, E_c-0.16 eV, E_c-0.28 eV and E_c-0.54 eV, were found. The dominant recombination centre is the energy level E_c-0.28 eV. Carrier lifetime is influenced by iridium centres at high current densities (high injection conditions). The iridium centre capture cross-section rapidly decreases with increasing temperature, which can result in a limit of efficiency of iridium centres around 120 °C. The iridium diffusion can be used for fabrication of fast diodes with relatively soft reverse recovery characteristics