Temperature-dependent trapping behaviors of thin-nitrided oxide films

This work studies the properties of oxide traps by measuring the temperature dependence of the current-voltage (IV) characteristics for temperature ranging from 100 to 423 K. Results show that the trapping behaviors of the nitrided oxides have different temperature dependencies from those of conventional thermal oxides. For nitrided oxide at low electric fields (≈ 6 MV/cm), the temperature dependencies of the IV curves for temperature less than 400 K shows an activation energy in the range of 0.117 ≈ 0.168 eV. This effect is attributed to the shallow trap-assisted conduction. Poole-Frenkel or thermionic emission of trapped charges is significant for temperature greater than 400 K and the activation energy of the IV curves is about 0.143 eV. For nitrided oxide at high electric field and at low temperature lower than 130 K, shallow trap-assisted two- step tunnelling of electrons is very significant. In studying the temperature dependencies of the electronic trapping in nitrided oxides, we found that the density of trapped charges decreases as large as 36.7% for temperature rising from 100 to 423 K. It indicates that the shallow trap density in nitrided oxide is significantly larger than that of thermal oxides.