Optical and electronic properties of TiCxNy films

The optical and electronic properties of TiCxNy(x+y similar to1,0 <1) thin films have been investigated by spectroscopic ellipsometry in the 1.5-4.5 eV energy range and by valence band x-ray photoemission spectroscopy as a function of the composition. The dielectric functions measured in the energy range of intraband transitions are analyzed in terms of a Drude-like approximation. Both the free plasma energy and the damping constant are observed to depend on the nitrogen content of the samples, suggesting a certain tunability of the optical and electronic properties of these films. Analysis of the valence band reveals that the C 2p band shifts toward higher binding energies upon an increase of the nitrogen content, in good agreement with the shift observed in the minimum of the optical reflectivity associated with the threshold of the interband transitions. The enhancement of the metallic character of the films as the nitrogen content increases is also evidenced by x-ray photoemission spectroscopy as a continuous intensity growth of the conduction band at the Fermi level. (C) 2001 American Institute of Physics.