Boron and phosphorus diffusion in strained and relaxed Si and SiGe

The diffusion of boron and phosphorus has been investigated in SiGe grown by molecular beam epitaxy. The analysis was done in relaxed Si1−xGex for x=0, 0.01, 0.12, and 0.24 for B and x=0, 0.07, 0.12, 0.24, and 0.40 for P. B diffusion in relaxed samples shows little effect of changing the Ge content while for P diffusion, increasing Ge content increases the diffusion coefficient from Si up to Si0.76Ge0.24. This is explained by a pairing of B and Ge atoms retarding the diffusion. B diffusion in compressively strained Si0.88Ge0.12 and Si0.76Ge0.24 and tensile strained Si and Si0.88Ge0.12 was also investigated. Compressive strain was found to decrease the diffusion coefficient of B and tensile strain to increase it.