Effects of stress on interdiffusion in Si 1−x Ge x /Si superlattices

The effects of grown in stress and applied external stress on the interdiffusion behaviour in long period Si_0·7Ge_0·3/Si are examined using X-ray diffraction and Raman spectroscopy. Both symmetrically and asymmetrically strained superlattices have been examined, and activation energies for interdiffusion of 3·9 and 4·6 eV, respectively have been obtained. In addition, an enhanced interdiffusion was also measured when the asymmetrically strained superlattice was subjected to an external tensile stress during annealing. In both types of superlattice, enhanced inter diffusion was measured whenever the Si barrier layers experienced tensile stress during annealing. The Raman results indicate that enhanced Ge diffusion into the Si barriers occurs when these barriers are placed under tensile stress. The result is discussed in terms of the kinetics of defect formation and motion in the strained Si barriers.

MST/3292