In this article, helped by finite element simulations, we show that, properly designed, planar-rotator microstructures can be used to simultaneously determine the uniform and gradient residual stresses in thin films in the limit of linear residual stress form. TEM characterization studies on the defect formation and propagation as a function of 3C-SiC/Si thickness revealed that the linear stress approximation in such a hetero-epitaxial thin film is wrong. With finite element modeling four different stress relationships were studied and compared. This study shows that the new approximation forms of the total residual stress function result in a better fit of the experimental data and reduces the disagreement between theory and experiments.