Interface recombination velocity measurement in SiO$_2$/Si

The photothermal technique has been used in its orthogonal configuration in order to determine the interface recombination velocity between SiO$_2$ ultra-thin film and Si substrate. This investigation has been performed by studying the variation of the photothermal signal according to the square root modulation frequency of the pump light beam. A general one-dimensional theoretical model taking into consideration the nonradiative recombination process has been developed. The interface recombination velocity has been evaluated by fitting the experimental curves of the phase and normalized amplitude of the photo-thermal signal with the corresponding theoretical ones.