A SiGe film with 50 nm in thickness is grown heteroepitaxially on a 750 um (001) Si substrate. The curvature of the substrate is k1 = -4.4 x 10-mat room temperature after the growth. The curvature of the structure changes to K2 = -20.5 x 10-m- when the substrate is thinned from the back to be 400 um. We assume the elastic properties of the film and the substrate are the same: C11 = 166.2, C12 = 64.4, and C44 = 79.8 Gpa. Determine the following quantities. (a) The curvature of the Si substrate prior to the growth. (b) The biaxial strain in the SiGe film