The local distributions of stress states and C bonding in film samples were studied by means of micro-Raman spectroscopy. Large changes in the intensity, line-shape, and peak position of the Raman line were observed to occur close to the grain boundary. A characteristic feature of such a region was a 1326/cm Raman peak. Its presence suggested that defect incorporation at the grain boundary could promote a symmetry-modification from cubic to hexagonal. Close to inter-grain locations, large anisotropic stresses also induced frequency-splitting of the Raman line. Stress configurations were analyzed which were consistent with the detection of an almost unshifted component and of a largely frequency-changing mode.

Micro-Raman Fingerprint of Grain Boundary in [100] Oriented Diamond Films: Stress Distribution and Diamond Phases. M.C.Rossi: Applied Physics Letters, 1998, 73[9], 1203-5