Characterization of vacancy-type defects and phosphorus donors introduced in 6H-SiC by ion implantation

Positron annihilation measurements using monoenergetic positron beams were performed to study vacancy-type defects introduced into 6H-SiC by implantation of phosphorus ions, P, and the interactions among such defects due to annealing up to 1500 degrees C. In as-implanted samples, residual defects are found to be mainly divacancies. The annealing behavior of these defects can be divided into three annealing stages, in which a change in the mean defect size and an elimination of defective layers are observed. An increase of the mean defect size in stage I (RT - 700 degrees C) can be attributed to the combination of vacancy-type defects due to the migration of monovacancies. In stage II (700-1000 degrees C); the formation of large vacancy clusters is observed. In contrast, a decrease in the mean size of vacancy clusters occurs in stage III (1000-1400 degrees C). Almost all vacancy-type defects are annealed out at 1400 degrees C. The electron concentration at RT increases markedly with annealing temperature up to approximate to 1400 degrees C, which is explained in terms of the removal of vacancy-type defects in the implanted layer and the electrical activation of implanted P atoms by annealing.