The Sb diffusion coefficient, in Si1–xGex/Si1–yGey(001) heterostructures grown by molecular beam epitaxy, was measured at 700 to 850C for Ge compositions ranging from 0 to 20% and for biaxial pressures ranging from -0.8 to 1.4GPa (table 28). A quantitative separation was made of the composition and biaxial stress effects. It was shown that the Sb lattice diffusion coefficient increased with Ge concentration in relaxed layers, or at constant biaxial pressure, and increased with compressive biaxial stress or decreased with tensile biaxial stress at a constant Ge composition. The enhancement of Sb lattice diffusion in Si1–xGex layers, in epitaxy on Si(001), was therefore due to the cooperative effect of Ge composition and induced compressive biaxial stress. The former effect was predominant. The activation volume of Sb diffusion in Si1–xGex layers was deduced from the variation in the Sb diffusion coefficient with biaxial pressure, and was found to be negative. The sign of the activation volume, its absolute value and its temperature-variation confirmed the predictions, of a thermodynamic model, that the activation volume was reduced to the relaxation volume; under a biaxial stress.

Sb Lattice Diffusion in Si1–xGex/Si(001) Heterostructures - Chemical and Stress Effects. A.Portavoce, P.Gas, I.Berbezier, A.Ronda, J.S.Christensen, A.Y.Kuznetsov, B.G.Svensson: Physical Review B, 2004, 69[15], 155415 (7pp)