Retardation of boron diffusion in SiGe alloy

We investigate the effect of Ge on the retardation of B diffusion in SiGe alloys through first-principle calculations, and find that the Ge bonding effect is most significant in the nearest-neighborhood of B. The B dopant diffuses from a self-interstitial–B pair via an interstitialcy mechanism for neutral charge state, while a kick-out mechanism is also possible for 1+ charge state. The migration and activation energies depend on the number and positions of the Ge atoms and are generally enhanced by the presence of Ge, reducing the B diffusivity.