Diffusion of boron in germanium at 800–900°C

Diffusion of $\mathrm{B}$ in $\mathrm{Ge}$ is studied in the temperature range $800–900°\mathrm{C}$ using implantation doping and B doped epitaxial Ge layers. Concentration profiles before and after furnace annealing were obtained using high resolution secondary ion mass spectroscopy (SIMS). Diffusion coefficients were calculated by fitting the annealed profiles using TSUPREM. We obtained diffusivity values which are at least two orders of magnitude lower than the lowest values previously reported in the literature. Using our values an activation energy of $4.65(\pm 0.3)\mathrm{eV}$ is calculated. Present experimental results suggest that interstitial mediated mechanism should be considered for $\mathrm{B}$ diffusion in $\mathrm{Ge}$ in accordance with recent theoretical calculations. Annealed SIMS profiles also suggest that $\mathrm{B}$ solid solubility in $\mathrm{Ge}$ is $\sim 2\times {10}^{18}{\mathrm{cm}}^{-3}$ at $875°\mathrm{C}$ which agrees with literature values.