Interaction of thermal strains during the growth of SiGe strained layers on Si was analyzed. A formula for the critical layer thickness was obtained which was based upon an energy balance. This took account of thermal strains, under the assumption that the screw dislocation energy density was equal to the sum of the areal strain-energy density and the thermal strain-energy density. The relationship between the Ge content, and the thermal expansion coefficient that was associated with thermal strain, was linear.

J.Huang, Z.Ye, H.Lu, D.Que: Journal of Applied Physics, 1998, 83[1], 171-3