Laser annealing of Bi implanted <111> and <100> silicon

The influence of surface orientation in Bi implanted silicon, annealed by Q-switched ruby laser pulse irradiation was investigated. Depth distributions and lattice location of the Bi atoms were obtained using⁴He backscattering and channeling techniques and the electrical behavior studied by sheet resistance measurements. The dopant profiles show partial surface accumulation and in-depth broadening without influence of the substrate orientation. These profiles can be fitted by a numerical calculation based on the normal freezing model with an interfacial segregation coefficient much higher than the equilibrium one. The impurity atoms located in the in-depth profile are shown to be electrically active when their maximum concentration does not exceed 10²⁰ atoms/cm³.