Dielectric Properties of Ti, TiO2 and TiN from 1.5 to 60 eV Determined by Reflection Electron Energy Loss Spectroscopy (REELS) and Ellipsometry

Abstract

The dielectric properties of metallic Ti and thin films of TiO2 and TiN in the energy range from 1.5 to 60 eV have been determined by quantitative analysis of the respective electron energy loss spectra in the reflection mode (REELS). The energy loss function (ELF) of every material, that is proportional to Im {1/ε}, is obtained by trial and error until a good quantitative agreement between the simulated and experimental inelastic electron scattering cross‐sections at three different primary electron energies (i.e. 0.5, 1 and 1.5 keV) is achieved. Kramers‐Kronig transformation is then used to obtain real and imaginary parts of the dielectric function ε(ω). In addition, spectroscopic ellipsometry was used to improve the ELF in the 1.5 to 4.5 eV energy range where it is strongly affected by the experimental energy resolution and the presence of the elastic peak. The characteristic differences among the spectra of the particular compounds are discussed in terms of different electronic properties.

Two-step nitridation of photocatalytic TiO2 films by low energy ion irradiation

“…2. In both spectra, the loss intensity of 6 eV corresponds to the interband transition from valence band to Ti 3p and the peak at 11 eV the bulk plasmon, which are consistent with the literatures [15]. For the surface nitrided with 0.2 keV ions, a broadening of the peak at 6 eV and a decrease in the loss intensity of 11 eV can be observed, which may be due to the mixing of N 2p with the valence band and the distribution of N atoms in the TiO 2 , respectively.…”

Collective electronic excitations in Ti and Zr and their dihydrides

“…The value of 14.5 eV for the bulk plasmon energy reported in Ref. [76] seems to contradict our findings. A most intense experimental peak at 18.3 eV was then interpreted as due to 3d → 4sp interband transitions [77].…”

“…According to our findings, this experimental peak may correspond to the bulk plasmon in Ti. At lower energies, two oscillators were identified [76] at 5 and 9 eV, which were associated with 3d → 3d and 3d → 4p transitions [77]. On the other hand, the value of 13.7 eV reported in Ref.…”

“…On the other hand, the most relevant feature of the experimental loss function measured in Ref. [76] is a double feature at 14.5 and 18.3 eV. A peak at 14.5 eV was assigned to the bulk plasmon according to the behavior of 1 at that energy, which shows a clear zero crossing and is accompanied with a small value of 2 .…”

Optical and electronic properties of TiCxNy films

“…From a fundamental point of view, their high hardness and melting point are explained in terms of the strong overlap between the anionic N 2p or C 2p orbital with 3d electrons of titanium. [7][8][9][10][11][12][13][14][15][16][17][18][19] Additionally, their good conductivity ͑especially in the case of TiN͒ is a result of the intersection of the Fermi level with the remaining Ti 3d electrons in the valence band that promotes the appearance of nearly free electrons. [7][8][9][10][11][12][13][14][15][16][17][18][19] The electronic structure of TiC and TiN has been experimentally studied by x-ray photoelectron spectroscopy ͑XPS͒, electron energy loss spectroscopy ͑EELS͒, photoemission spectroscopy ͑PES͒, and x-ray Absorption Spectroscopy ͑XAS͒, 7-15 as well as under different theoretical approaches.…”