Origin of Interface States and Oxide Charges Generated by Ionizing Radiation

The randomly located trivalent silicon atoms are shown to account for the thermally generated interface states at the SiO₂-Si interface. The interface state density is greatly reduced in water containing ambients at low temperatures (450°C) by forming trivalent silicon hydroxide bonds. Interface states are regenerated when the ≡Si-OH bonds are broken by ionizing radiation and the OH ions are drifted away. In the bulk of the oxide film, the trivalent silicon and the interstitial oxygen donor centers are shown to be responsible for the heat and radiation generated positive space charge build-up (oxide charge) in thermally grown silicon oxide.