Differences between charge trapping states in irradiated nano-crystalline HfO2 and non-crystalline Hf silicates

This paper provides an explanation for qualitative differences between radiation-induced charge trapping states in nano-crystalline HfO2 and non-crystalline Elf silicate alloys in high-kappa gate stacks by combining electrical measurements with spectroscopic studies and theory. Differences in the observed electrical response to X-ray and gamma-ray irradiation are consistent with fundamental differences in electronic structures between high-kappa dielectrics that are nano-crystalline and have a film thickness in excess of 4 nm, and high-kappa dielectrics that are non-crystalline and devoid of grain boundaries. Oxygen vacancy and interstitial defects are shown to be natural candidates for the electron and hole traps in these high-kappa dielectrics.