Stress reduction and bond stability during thermal annealing of tetrahedral amorphous carbon

A comprehensive study of the stress release and structural changes caused by postdeposition thermal annealing of tetrahedral amorphous carbon (ta-C) on Si has been carried out. Complete stress relief occurs at 600-700 degrees C and is accompanied by minimal structural modifications, as indicated by electron energy loss spectroscopy, Raman spectroscopy, and optical gap measurements. Further annealing in vacuum converts sp(3) sites to sp(2) with a drastic change occurring after 1100 degrees C. The field emitting behavior is substantially retained up to the complete stress relief, confirming that ta-C is a robust emitting material. (C) 1999 American Institute of Physics. [S0021-8979(99)05910-1].