Effects of substrate temperature on the properties of tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films were deposited by the filtered ca thodic vacuum are technique with substrate temperature ranging from 25 to 4 00 degrees C. A transition from diamond-like properties to graphitic proper ties was observed for deposition above a threshold temperature value, which is found to increase from 200 to 300 degrees C for films deposited at diff erent ion energies of 60 and 100 eV, respectively. These changes of propert ies upon transition include a change in the surface roughness, compressive stress and Raman spectra. The variation of results is consistent with the s ubplantation model, which emphasizes the role of carbon atoms trapped in th e subsurface layers in the evolution of a dense sp(3) rich phase at room te mperature. At higher temperature, diffusion of carbon atoms to the surface of the evolving film releases internal stress and leads to the formation of a graphitic sp(2) phase. (C) 1999 Elsevier Science S.A. All rights reserve d.