Photoinduced trap generation at the Si-SiO2 interface

We report on the permanent modification of the second-order nonlinear (SHG) response of the Si-SiO2 interface upon irradiation of oxidized Si(100) and Si(111) samples with femtosecond laser pulses of nanojoule pulse energy at the wavelength of 780 nm (1.6eV). We attribute this effect to a dc-field-induced SH contribution which results from the creation of new oxide traps by a photoinduced damage process. The damage process occurs, with a significantly lower efficiency, also under cw irradiation; the experimental results, however, rule out a thermal origin of the effect as well as a multiphoton effect. © Springer-Verlag 1998.