Dopant Effect On NiGe Texture During Nickel Germanide Growth

摘要

In this paper, we report on the solid state reactions of Ni thin films (6nm to 12nm) deposited on Ge (001). Especially, the influence of the substrate dopants (As and BF_2) is investigated. TEM and SIMS analyses point out the presence of an additional phase at the NiGe/Ge interface. EELS and SIMS measurements reveal that this phase contains Ni and Ge. On the another hand, ex-situ XRD spectra allows to determine a change in NiGe texture with Ge(001) doped or undoped. In situ XRD confirms that the kinetics shifts from simultaneous to sequential growth of nickel germanides, as predicted previously. Moreover, a recrystallization of NiGe is observed only on the undoped substrate. This recrystallization can be attributed to a contribution of a stress term in addition of the surface energy. This stress term becomes minor when temperature increases and Ni-rich phase is completely consumed. The presence of dopants, probably at the NiGe/Ge interface could reduce this stress and thus the recrystallization.