Residual stresses in chemical vapor deposition free-standing diamond films by X-ray diffraction analyses

The macroscopic residual stress state on thick self-supported diamond films is studied using X-ray diffraction ‘sin2ψ’ method. Both compressive and tensile stresses are reported. In relation with scanning electron microscopical analyses, we show that the macroscopic residual stresses cannot be explained by the usual models involving the grain boundaries density. To measure micro-strains, complementary studies were done by profile analyses based on integral breadths measurements of the diffraction peaks. The presence of macroscopic stresses and micro-strains is consistent with the models, which involve a non-uniform distribution of impurities inside the grains, leading to non-uniform long-range stresses. It suggests that the micro-stresses are mainly located at the vicinity of the facets edges and, when they are high, provoke the appearance of cracks which propagate along the edges.