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| 2. |
- Sarakinos, Kostas, et al.
(författare)
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Structural factors determining the nanomechanical performance of transition metal nitride films
- 2005
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Konferensbidrag (refereegranskat)abstract
- Chromium nitride (CrN) and Titanium nitride (TiN) thin films were deposited employing unbalanced magnetron sputtering (UBMS) for various values of substrate bias voltage (V-b). The structural characterization of the films in terms of phase identification and the density determination was achieved utilizing X-Ray techniques (XRD and XRR respectively), while the internal stresses were calculated by the change of the substrates curvature using Stoneys equation. The nanomecahnical properties of the films (hardness and elastic modulus) were investigated using the Nanoindentation (NI) technique in the Continuous Stiffness Measurement (CSM) configuration. According to the NI results the hardness of the films ranges between between 15-25 GPa while the elastic modulus between 180-250 GPa. ne analysis revealed that the hardness of the films is maximum when their orientation is pure (either [111] or [100]), while it is minimized under mixed orientation regime. Furthermore, the hardness of the films increases as the internal compressive stresses and the mass density increase. The latter can be validated through the comparison of the results concerning the above films to reported results for TiN films prepared by balanced magnetron sputtering (BMS).
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| 3. |
- Logothetidis, S, et al.
(författare)
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Investigation of bilayer period and individual layer thickness of CrN/TiN superlattices by ellipsometry and X-ray techniques
- 2006
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 200:22-23, s. 6176-6180
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Tidskriftsartikel (refereegranskat)abstract
- CrN/TiN superlattice (SL) coatings were prepared employing reactive magnetron sputtering in unbalanced configuration. The coatings were deposited in a mixed Ar/N-2 atmosphere rotating the substrate holder, located at the centre of the deposition chamber. Through the rotation, the substrate was sequentially exposed in two diametrically located Cr and Ti targets (purity 99.95%) leading to the deposition of the CrN and TiN single layers, respectively. The deposition was carried out at various values of substrate bias voltage and substrate rotation speed. The microstructure of the SL coatings was investigated in terms of the thickness of the individual CrN and TiN single layers and the bilayer period A, namely the sum of the thickness of two sequentially CrN and TiN layers. A values were calculated employing X-ray diffraction (XRD) at both low and high diffraction angles. Moreover, the high-angle XRD patterns enabled the determination of the single CrN and TiN layer thickness. In addition, the thickness of the single layers was determined from Spectroscopic Ellipsometry using the Bruggeman effective medium approximation. The results reveal good agreement between the various techniques.
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| 4. |
- Logothetidis, S, et al.
(författare)
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The effect of crystal structure and morphology on the optical properties of chromium nitride thin films
- 2004
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 180, s. 637-641
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Tidskriftsartikel (refereegranskat)abstract
- We study the microstructure of various CrxNy (1 less than x less than 2, y similar to 1) coatings grown by unbalanced reactive magnetron sputtering (UBRMS), using X-ray diffraction (XRD) and reflectivity (XRR). The coatings consist of various Cr-N phases, depending on the growth conditions. XRD has shown that a Cr adhesion layer below CrxNy eliminates the stress and promotes the growth of bigger grains. XRR determined the film density, which can be used also for the phase identification. We found that the UBRMS can produce single-phase CrN and Cr2N coatings with density equivalent to the corresponding single-crystals. The optical properties of the coatings were studied by spectroscopic ellipsometry (SE). The variations of optical properties of CrxNy coatings have been evaluated from SE data using the combined Drude-Lorentz model, which describes the optical response of the conduction and valence electrons, respectively, and provides the conduction electron density and the energy positions of the interband transitions. Finally, the optical properties were used to quantify the volume fractions of each phase using effective medium theories.
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