Surface recombination velocity in silicon substrates determined from light beam induced current measurements

We show a simple method to determine the surface recombination velocity of silicon substrates from light beam induced current (LBIC) measurements. With this method we have studied the possible passivation effects due to SiN obtained by PECVD as compared to SiO₂ thermally grown and a combination of thermal SiO₂ with PECVD SiN. From LBIC measurements and by fitting the data to a realistic mathematical model we were able to determine both the diffusion length and the surface recombination velocity for silicon substrates covered with different passivating films. In this way we could determine that a combination of thin thermal SiO₂ with SiN is a better surface passivant than pure SiN films, but is not as good as a thick thermal SiO ₂. However, it is expected that SiN or SiO₂/SiN layers may be optimized in order to have similar passivation as a thick thermal SiO₂ film on top of silicon. In this case, a simple technique to determine the surface recombination velocity, such as the one presented here, should be very useful