EVOLUTION OF THE CRYSTALLOGRAPHIC POSITION OF AS IMPURITIES IN HEAVILY-DOPED SI CRYSTALS AS THEIR ELECTRICAL-ACTIVITY CHANGES

Arsenic impurities in silicon can be electrically activated beyond the ir electrical solubility to as high as 4x10(21)/cm(3) by ion implantat ion and laser melting; further annealing decreases this activity to it s equilibrium saturation level. To characterize the deactivation proce ss, we used x-ray standing-wave spectroscopy. Hall effect, and seconda ry-ion-mass spectroscopy. Our results indicate that the As impurities remain in substitutional positions even after 85% of the activation ha s been lost, so deactivation cannot be due to As migration to intersti tial sites or to large precipitates. (C) 1996 American Institute of Ph ysics.