Novel diffusion phenomenon of dopants in silicon at low temperatures

We present the first experimental observation of an asymmetric diffusion behavior of dopant atoms in silicon. Point defects were injected into the silicon by formation of the silicide compound ${\mathrm{Pd}}_2$Si at 200 °C. This flux of point defects led to an asymmetric broadening of a narrow buried layer of dopant atoms, with diffusion occurring preferentially towards the silicide/silicon interface. The asymmetric diffusion behavior of the dopant atoms is a general phenomenon since we observed it for n- as well as p-type dopant. We discuss several mechanisms that could be responsible for this new diffusion phenomenon.