AES, EELS and XPS characterization of Ti(C, N, O) films prepared by PLD using a Ti target in N_2, CH_4, O_2 and CO as reactive gases

摘要

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 (TiO_x), N_2 (TiN_x), CH_4 (TiC_x), CO (TiC_xO_y), N_2 + CH_4 (TiC_xN_y) and CO + N_2 (TiC_xN_yO_z). After depositions, every film is characterized in situ by Auger, electron-energy loss and X-ray 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 + CH_4 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 + CH_4 mixture was ineffectively to produce TiC_xO_y films, yielding mostly TiO_2 with traces of embedded carbon. By using CO as reactive gas the TiC_xO_y films were completed. Also, a mixture of CO with N_2 was tested to produce quaternary TiC_xN_yO_z 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.