New insights into radiation-induced oxide-trap charge through thermally-stimulated-current measurement and analysis [MOS capacitors]

An analytical model with no free parameters has been developed which accurately describes thermally-stimulated-current (TSC) measurements spanning more than a factor of 50 in average heating rate. The model incorporates Schottky electric-field-induced barrier lowering and a temperature-dependent `attempt-to-escape frequency´ equal to ~10 ¹⁴ Hz at 300°C. Applying this model to TSC measurements provides significantly improved estimates of the energy distribution of trapped holes in irradiated SiO₂. All devices examined, including soft and (wet and dry) hard oxides from five process technologies, show similar energy distributions, with a minor peak at ~1.2 eV and a broad major peak centered ~1.7-2.0 eV above the SiO₂ valance band. It is found that the trapped-electron density in irradiated SiO₂ is proportional to the trapped-hole density over a wide range of irradiation conditions