LATTICE LOCATION OF ER IN GAAS DETERMINED FROM MONTE-CARLO SIMULATIONOF ION CHANNELING SPECTRA

We have determined the lattice location of Er doped into GaAs single c rystals grown by metal-organic chemical vapor deposition (MOCVD) using the ion channeling effect. A strong flux peaking is observed for 2.0 MeV He+ ions incident along the GaAs [110] axis, whereas a significant shadowing effect is seen for the [111] and [100] incidence. Monte Car lo simulation of ion trajectories has revealed that almost all Er atom s occupy the lattice position shifted by 0.6 angstrom from the tetrahe dral interstitial site toward the hexagonal site. This suggests that t he dopant Er atom is loosely combined with an impurity carbon atom rep lacing a lattice As atom. In this paper, we propose a new multistring model to simulate ion trajectories and compare it with the single row approximation in the context of accuracy and computing time.