Diffusion of ion-implanted boron in germanium

The diffusion of boron (B) in germanium (Ge) is studied. B was introduced in Ge wafers by ion implantation, and concentration profiles after furnace annealing were obtained using secondary ion mass spectroscopy. The diffusion coefficient and solid solubility of B in Ge has been calculated to be 1.5(±0.3)×10−16 cm2/s and 5.5(±1.0)×1018/cm3, respectively, at 850 °C by fitting experimentally obtained profiles. This value of diffusion coefficient is at least two orders of magnitude lower than the minimum value reported in the literature for B diffusion in Ge. The results are significant as they question the general agreement about vacancy diffusion as the mechanism responsible for diffusion of B in Ge.