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 approximately 10/sup 14/ Hz at 300 degrees C. Applying this model to TSC measurements provides significantly improved estimates of the energy distribution of trapped holes in irradiated SiO/sub 2/. All devices examined, including soft and (wet and dry) hard oxides from five process technologies, show similar energy distributions, with a minor peak at approximately 1.2 eV and a broad major peak centered approximately 1.7-2.0 eV above the SiO/sub 2/ valance band. It is found that the trapped-electron density in irradiated SiO/sub 2/ is proportional to the trapped-hole density over a wide range of irradiation conditions.<
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