MD simulation of ion implantation damage in AlGaAs: II. Generation of point defects

Classical molecular dynamics computer simulations using a modified Tersoff potential are used to investigate the generation of point defects in AlxGa1−xAs crystals caused by Al, Ga and As recoils of energies in the range of 50-400 eV. The crystals are kept at room temperature and the composition x is varied between zero and one. The results for the numbers of the different vacancies, interstitials and antisites as functions of the recoil energy and the composition x are given as analytical expressions. In addition, the rates for the formation of the different antisites from the corresponding vacancies and interstitials and the recombination rates for Al, Ga and As are determined. For the generation of vacancies and interstitials (total numbers), the results confirm roughly the Kinchin-Pease formula, however, the factor deviates from 0.4 and it depends remarkably on the composition x. The results and the special role of the Al atoms are discussed.