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

Abstract

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 x O y ), N 2+CH 4 (TiC x N y ) and CO+N 2 (TiC x N y O 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 x O y films, yielding mostly TiO 2 with traces of embedded carbon. By using CO as reactive gas the TiC x O y films were completed. Also, a mixture of CO with N 2 was tested to produce quaternary TiC x N y O 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.