DEFECT EVALUATION OF HEAVILY P-DOPED SI EPITAXIAL-FILMS GROWN AT LOW-TEMPERATURE

Heavily P-doped epitaxial Si films with carrier concentration of 3 x 1 0(21) cm-3 have been successfully grown by plasma chemical vapor depos ition using a gas mixture of SiH4, SiF4, H-2 and PH3 at a very low tem perature of 250-degrees-C. From the annealing characteristics of heavi ly P-doped Si films, it was found that the electron concentration decr eased once after annealing at 600-degrees-C but increased subsequently upon raising the annealing temperature. The possibility of the format ion of a vacancy-type defect complex, typically (V-P4), a vacancy surr ounded by four phosphorus atoms, was proposed to interpret this phenom enon. Furthermore, a positron annihilation experiment was employed to investigate this vacancy-type defect in Si films and good agreement wa s obtained between thermodynamical calculation based on the V-P4 model and the positron annihilation experiment.