Radiation damage studies in gate oxides

Detailed investigation of the effects of Gamma-ray irradiation on the electrical properties such as current-voltage arid capacitance-voltage characteristics in thermally grown SiO2 films in the thickness range of 15 to 120 nm on silicon substrates is presented in this thesis. The structures used in this study are Al/Poly/SiO2/Si/Al and Al/SiO2/Si/Al MOS capacitors. Based on the electrical characterization studies, we observe that irradiation causes generation of positive charges in the oxide leading to a shift of the high frequency Capacitance-Voltage (C-V) curves. An increase in surface state density at the SiO2-Si interface with increase in radiation dose is also observed. Static current-voltage (I-V) characteristics lead to a further insight in the formation of radiation induced oxide traps. Fowler-Nordheim tunneling in irradiated MOS structures is investigated