Deep energy levels in power diodes introduced by iridium diffusion

Abstract

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/sub c/-0.16 eV, E/sub c/-0.28 eV and E/sub c/-0.54 eV, were found. The dominant recombination centre is the energy level E/sub 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 /spl deg/C. The iridium diffusion can be used for fabrication of fast diodes with relatively soft reverse recovery characteristics.