Contactless ultra-fast laser probing of radiation-induced leakage current in ultra-thin oxides

Radiation induced leakage current in a variable-thickness SiO/sub 2/-on-Si structure (1.0-6.5 nm) is detected and characterized by a novel technique, time-dependent electric field-induced second-harmonic generation (EFISH). The role of second-harmonic generation (SHG) for in situ monitoring of the DC field across the oxide and its utility in understanding the dynamics of the carriers in response to their photo-injection is discussed. Plausible mechanisms responsible for radiation-induced leakage current through thin oxides are used to explain the experimental results.