Atomistic simulation of ion channeling in heavily doped Si:As

The structure of vacancy-As complexes (V-Asm, with m = 1, 4) is calculated by first-principles methods and implemented in Monte Carlo (MC) simulation of Rutherford backscattering-channeling (RBS-C) spectra. Using this procedure the atomic position of As, inferred from the model of the complex, is no longer treated as a free parameter of the simulation, as it usually occurs within MC fitting of RBS-C spectra. Moreover, physical effects which influence the backscattering and dechanneling yields of ions, such as the lattice distortion around the vacancy, are naturally taken into account in the simulation. We investigate the sensitivity of RBS-C to the different complex models and report an example of the application of the method to the case of heavily doped Si:As equilibrated at high temperature. The comparison of simulated and experimental angular scans shows that while the hypothesis of inactive As trapped in V-As4 clusters is consistent with experimental observations, the presence of a significant amount of V-As clusters is unlikely.