THE EFFECT OF NITROGEN ON THE MICROSTRUCTURE AND THE LUMINESCENCE PROPERTIES OF A-C-H THIN-FILMS

In this paper, a comparative study of a-C:H films and low N content a- C:H:N films is performed by infrared, photoluminescence, and ultraviol et, visible, near-infrared spectra. Comparing the properties of as dep osited samples with those after annealing cycles at increasing tempera ture, it is found that nitrogen weakens some C-H bonds, as confirmed b y differential scanning calorimetric results. From the analysis of the IR peaks line-width, it is shown that the presence of nitrogen leads to a stress release. Moreover, we found experimental evidence for the weakening of C-H bonds due to the presence of nitrogen. In particular, a large scale rearrangement of the sp(3) carbon network: (probably a conversion from sp(3) to sp(2)) consequent to. the dehydrogenation of the sp(3) carbon sites, takes place. The effect of the stress in the s p(3) network upon sp(2) regions is evidenced by the change in the phot oluminescence properties and in the line-width of infrared peaks. Copy right (C) 1996 Elsevier Science Ltd.