Dielectric breakdown and Poole–Frenkel field saturation in silicon oxynitride thin films

Dielectric breakdown is studied in silicon oxynitride thin films varying in composition from SiN1.33 to SiO0.60N0.93. The films are observed to exhibit Poole–Frenkel emission as the dominant charge transport mechanism, with a compositionally dependent ionization potential ranging from 1.22 to 1.51 eV. The barrier lowering energy at the point of dielectric breakdown is independently determined to be likewise compositionally dependent, with the energies correlated to within ∼2kT of the ionization potential. Field saturation-induced trap ionization is discussed as a means to negate carrier scattering from bulk traps as an impediment to impact ionization and dielectric breakdown.