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

The macroscopic residual stress state on thick self-supported diamond films is studied using X-ray diffraction 'sin(2)psi' method. Both compressive an d tensile stresses are reported. In relation with scanning electron microsc opical analyses: we show that the macroscopic residual stresses cannot be e xplained by the usual models involving the grain boundaries density. To mea sure micro-strains, complementary studies were done by profile analyses bas ed on integral breadths measurements of the diffraction peaks. The presence of macroscopic stresses and micro-strains is consistent with the models, w hich involve a non-uniform distribution of impurities inside the grains, le ading to non-uniform long-range stresses. It suggests that the micro-stress es are mainly located at the vicinity of the facets edges and, when they ar e high, provoke the appearance of cracks which propagate along the edges. ( C) 2000 Elsevier Science S.A. All rights reserved.