Annealing effects on near stoichiometric a-SiC:H films

The effect of thermal annealing on near stoichiometric hydrogenated amorphous silicon carbide films (a-SixC1-x:H) deposited onto the cathode of a r.f. glow discharge system is reported. Similar results were obtained for all samples regardless of their silicon content. in the range 0.45 < x < 0.55. The density of Si-H bonds starts to decrease at low annealing temperatures, whereas C-H bonds are only affected at temperatures higher than 500 degrees C. It was observed that the loss of hydrogen from the films results in an increase in density of Si-C bonds. Raman results suggest that C=C bonds present inside the material are probably isolated or located in very small clusters, in contrast to low silicon content samples or pure a-C:H films. Effusion experiments showed that hydrogen from the internal surface of voids is released at low temperatures and, therefore, that the films have a porous structure. Annealing at high temperatures showed that, although a Si-C-rich network is formed, graphitization of carbon clusters still occurs. The comparison of IR and Raman results showed that the graphitization process is not related to hydrogen loss. (C) 1999 Elsevier Science S.A. All rights reserved.