AES, EELS and XPS characterization of Ti(C, N, O) films prepared by PLD using a Ti target in N2, CH4,O2 and CO as reactive gases

Titanium-based films were grown on (1 0 0)-Si substrates by the pulsed laser deposition (PLD) method using a Ti target in reactive atmospheres. The films were grown in vacuum (Ti-film), O-2 (TiOx), N-2 (TiNx), CH4 (TiCx), CO (TiCxOy), N-2 + CH4 (TiCxNy) and CO + N-2 (TiCxNyOz). After depositions, every film is characterized in situ by Auger, electron-energy loss and Xray photoelectron (XPS) spectroscopies. For the binary compounds the stoichiometry is regulated without difficulty by gas pressure during ablation. However, for ternary and quaternary compounds there is a tendency to produce chemically inhomogeneous films. For example, the ablation of Ti in a N-2 + CH4 environment results in a TiNC:C composite. In this case, the overabundance of nitrogen influences the segregation of carbon. In the other hand, the O-2 + CH4 mixture was ineffectively to produce TiCxOy films, yielding mostly TiO2 with traces of embedded carbon. By using CO as reactive gas the TiCxOy films were completed. Also, a mixture of CO with N-2 was tested to produce quaternary TiCxNyOz compounds. Based on these results, it is recommended that better control on film stoichiometry and chemical homogeneity can be achieved by using reactive gases with predetermined C:N:O ratios. (C) 2004 Elsevier B.V. All rights reserved.