The diffusion of B in SiGe strained layers on Si was studied as a function of annealing temperature and Ge content, and was shown to be characterized by a lower diffusivity when compared with unstrained Si. The influence of the Ge content upon dopant diffusion was also measured; thus demonstrating that the diffusivity of the B atoms was reduced upon increasing the Ge fraction in the strained layer. The reduced B diffusivity in the strained SiGe, relative to the dopant diffusivity in unstrained Si, was attributed to a change in the charged point-defect concentration which was caused by band-gap narrowing. Good agreement was found between the measured and simulated diffusivities by using the known band-gap for the strained layers.

N.Moriya, L.C.Feldman, H.S.Luftman, C.A.King, J.Bevk, B.Freer: Physical Review Letters, 1993, 71[6], 883-6