Impurity and stress distribution in diamond films investigated by laser excited Raman and luminescence spectroscopy.

Impuritiy and stress distribution in diamond films have been studied by microRaman and microphotoluminescence. Raman and PL lateral profiles reveal the existence of a large anysotropic stress at the grain boundary resulting in frequency splitting and linewidth variations of the TO phonon. The detection of an additional peak at 1326 cm(-1) related to exagonal diamond phases and the high intensity reached by the 1.68 eV PL band at the coalescence region between two grains give evidence of preferential incorporation of defects at the grain boundary regions. Similarly, Raman and PL depth profiles indicate that the non-diamond intergrain tissue, abundant close to the substrate, induces compressive stress and represents a preferential site for Si diffusion