| 1. |
- Greczynski, Grzegorz, et al.
(author)
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Strain-free, single-phase metastable Ti0.38Al0.62N alloys with high hardness: metal-ion energy vs. momentum effects during film growth by hybrid high-power pulsed/dc magnetron cosputtering
- 2014
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 556, s. 87-98
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Journal article (peer-reviewed)abstract
- A hybrid deposition process consisting of reactive high-power pulsed and dc magnetron cosputtering (HIPIMS and DCMS) from Ti and Al targets is used to grow Ti1-xAlxN alloys, with x similar to 0.6, on Si(001) at 500 degrees C. Two series of films are deposited in which the energy and momentum of metal ions incident at the growing film are individually varied. In both sets of experiments, a negative bias V-s ranging from 20 to 280 V is applied to the substrate in synchronous, as determined by in-situ mass spectrometry, with the metal-ion-rich part of the HIPIMS pulse. Ion momentum is varied by switching the HIPIMS and dc power supplies to change the mass m and average charge of the primary metal ion. Al-HIPIMS/Ti-DCMS layers grown under Al+ (m(Al) = 26.98 amu) bombardment with 20 less than= V-s less than= 160 V are single-phase NaCl-structure alloys, while films deposited with V-s greater than 160 V are two-phase, cubic plus wurtzite. The corresponding critical average metal-ion momentum transfer per deposited atom for phase separation is less than p(d)*greater than greater than= 135 [eV-amu](1/2). In distinct contrast, layers deposited in the Ti-HIPIMS/Al-DCMS configuration with Ti+/Ti2+ (m(Ti) = 47.88 amu) ion irradiation are two-phase even with the lowest bias, V-s = 20 V, for which less than p(d)*greater than greater than 135 [eV-amu](1/2). Precipitation of wurtzite-structure AlN is primarily determined by the average metal-ion momentum transfer to the growing film, rather than by the deposited metal-ion energy. Ti-HIPIMS/Al-DCMS layers grown with V-s= 20 V are two-phase with compressive stress sigma= -2 GPa which increases to -6.2 GPa at V-s= 120 V; hardness H values range from 17.5 to 27 GPa and are directly correlated with sigma. However, for Al-HIPIMS/Ti-DCMS, the relatively low mass and single charge of the Al+ ion permits tuning properties of metastable cubic Ti0.38Al0.62 N by adjusting V-s to vary, for example, the hardness from 12 to 31 GPa while maintaining sigma similar to 0.
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| 2. |
- Kukli, Kaupo, et al.
(author)
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Atomic layer deposition of Ru films from bis(2,5-dimethylpyrrolyl)ruthenium and oxygen
- 2012
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 520:7, s. 2756-2763
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Journal article (peer-reviewed)abstract
- Ru thin films were grown on hydrogen terminated Si, SiO2, Al2O3, HfO2, and TiO2 surfaces by atomic layer deposition from bis(2,5-dimethylpyrrolyl)ruthenium precursor and oxygen. The 4-20 nm thick films on these surfaces consisted of nanocrystalline hexagonal metallic ruthenium, regardless of the deposition temperature. At the lowest temperatures examined, 250-255 degrees C, the growth of the Ru films was favored on silicon, compared to the growth on Al2O3, TiO2 and HfO2. At higher temperatures the nucleation and growth of Ru became enhanced in particular on HfO2, compared to the process on silicon. At 320-325 degrees C, no growth occurred on Si-H and SiO2-covered silicon. Resistivity values down to 18 mu Omega.cm were obtained for ca. 10 nm thick Ru films.
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| 3. |
- Kukli, Kaupo, et al.
(author)
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Holmium and titanium oxide nanolaminates by atomic layer deposition
- 2014
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 565, s. 165-171
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Journal article (peer-reviewed)abstract
- Nanolaminate (nanomultilayer) thin films of TiO2 and Ho2O3 were grown on Si(001) substrates by atomic layer deposition at 300 degrees C from alkoxide and beta-diketonate based metal precursors and ozone. Individual layer thicknesses were 2 nm for TiO2 and 4.5 nm for Ho2O3. As-deposited films were smooth and X-ray amorphous. After annealing at 800 degrees C and higher temperatures the nanolaminate structure was destroyed by solid-state reaction to form Ho2Ti2O7. The films demonstrated diamagnetic or paramagnetic behaviour in the as-deposited state. After annealing, the films possessed net magnetic moment, allowing one to record saturation magnetization and weak coercivity.
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| 4. |
- Lagerqvist, Ulrika, et al.
(author)
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Morphology effects on exchange anisotropy in Co-CoO nanocomposite films
- 2015
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 576, s. 11-18
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Journal article (peer-reviewed)abstract
- Co-CoO composite films were prepared by solution chemical technique using amine-modified nitrates and acetates in methanol. We study how particle size and porosity can be tuned through the synthesis parameters and how this influences the magnetic properties. Phase content and microstructure were characterised with grazing incidence X-ray diffraction and electron microscopy, and the magnetic properties were studied by magnetometry and magnetic force microscopy. Composite films were obtained by heating spin-coated films in Ar followed by oxidation in air at room temperature, and the porosity and particle size of the films were controlled by gas flow and heating rate. The synthesis yielded dense films with a random distribution of metal and oxide nanoparticles, and layered films with porosity and sintered primary particles. Exchange anisotropy, revealed as a shift towards negative fields of the magnetic hysteresis curve, was found in all films. The films with a random distribution of metal and oxide nanoparticles displayed a significantly larger coercivity and exchange anisotropy field compared to the films with a layered structure, whereas the layered films displayed a larger nominal saturation magnetisation. The magnitude of the coercivity decreased with increasing Co grain size, whereas increased porosity caused an increased tilt of the magnetic hysteresis curve. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license
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| 5. |
- Lai, Chung-Chuan, et al.
(author)
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Synthesis and characterization of Zr2Al3C4 thin films
- 2015
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In: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 595, s. 142-147
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Journal article (peer-reviewed)abstract
- Zr2Al3C4 is an inherently nanolaminated carbide where layers of ZrC alternate with layers of Al3C2. Characterization of bulk samples has shown it has improved damage tolerance and oxidation resistance compared to its binary counterpart ZrC. Though a potential candidate for coatings applied for use in harsh environments, thin films of Zr2Al3C4 have not been reported. We have synthesized epitaxial Zr2Al3C4 thin films by pulsed cathodic arc deposition from three elemental cathodes, and have studied the effect of incident atomic flux ratio, deposition temperature, and choice of substrate on material quality. X-ray diffraction analysis showed that Zr2Al3C4 of the highest structural quality was obtained for growth on 4 H-SiC(001) substrate at 800 degrees C. Also, suppression of competing phases could be achieved on alpha-Al2O3(001) at elevated substrate temperatures. Very similar growth behavior to that of the well-known M(n+1)AX(n) phases - Al supersaturation, binary carbide intergrowth and high sensitivity to choice of substrate - indicates a strong connection between the two families of materials, despite their differences in structure and in chemistry. (C) 2015 Elsevier B.V. All rights reserved.
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| 6. |
- Landälv, Ludvig, 1982-, et al.
(author)
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Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings
- 2019
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 688
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Journal article (peer-reviewed)abstract
- Coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited by pulsed DC reactive sputter deposition on Si(100) at a temperature of 550 °C. XRD showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, 63–42 at.% V. At lower V-content, 18 and 7 at.%, a gamma-alumina-like solid solution was observed, shifted to larger d-spacing compared to pure γ-Al2O3. The microstructure changes from large columnar faceted grains for α-V2O3 to smaller equiaxed grains when lowering the vanadium content towards pure γ-Al2O3. Annealing in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating, which transformed to α-Al2O3 after annealing to 1100 °C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The latter decreased with increasing V-content, larger than 7 at.% V metal fraction. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings.
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| 7. |
- Lewin, Erik, et al.
(author)
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Carbide and nanocomposite thin films in the Ti-Pt-C system
- 2010
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In: Thin Solid Films. - : Elsevier B.V.. - 0040-6090 .- 1879-2731. ; 518:18, s. 5104-5109
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Journal article (peer-reviewed)abstract
- Thin films in the Ti-Pt-C system were deposited by non-reactive, DC-magnetron sputtering. Samples were characterised using X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy. A previously not reported metastable solid solution carbide, (Ti1-xPtx)C-y with a Pt/Ti ratio of up to 0.43 was observed. This solid solution phase was present both as single phase in polycrystalline samples, and together with amorphous carbon (a-C) in nanocomposite samples. Annealing of nanocomposite samples leads to the decomposition of the solid solution phase and the formation of a nc-TiCx/a-C/nc-Pt nanocomposite. Test sensors for automotive gas exhausts manufactured from such a three-phase material suffer from complete oxidation of the coating at 400 degrees C with no observed sensor activity.
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| 8. |
- Lunca Popa, Petru, et al.
(author)
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Structural, morphological, and optical properties of Bi2O3 thin films grown by reactive sputtering
- 2017
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 624, s. 41-48
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Journal article (peer-reviewed)abstract
- Bi2O3 thin films were grown using reactive RF sputtering from a metallic Bi target. The influence of various deposition parameters (substrate temperature, applied power on target and oxygen content in the working gas) on the morphology, structure and optical properties of films was investigated. Depending on the O-2/(Ar + O-2) ratio of the working gas, bismuth, delta-Bi2O3, alpha-Bi2O3 or a mixture of these phases can be deposited, with a narrow window for growth of [111]-oriented delta-Bi2O3 thin films. The delta-Bi2O3 phase is stable from room temperature up to 350 degrees C (in air), where an irreversible transition to alpha-Bi2O3 occurs. This phase transformation is also shown to occur during TEM sample preparation, because of the inherent heating from the ion-milling process, unless liquid -nitrogen cooling is used. (C) 2017 Published by Elsevier B.V.
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| 9. |
- Muehlbacher, Marlene, et al.
(author)
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Copper diffusion into single-crystalline TiN studied by transmission electron microscopy and atom probe tomography
- 2015
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 574, s. 103-109
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Journal article (peer-reviewed)abstract
- TiN/Cu bilayers were grown by unbalanced DC magnetron sputter deposition on (001)-oriented MgO substrates. Pole figures and electron back-scatter diffraction orientation maps indicate that both layers in the as-deposited state are single-crystalline with a cube-on-cube epitaxial relationship with the substrate. This is confirmed by selected area electron diffraction patterns. To study the efficiency of the TiN barrier layer against in-diffusion of Cu, we annealed samples at 900 degrees C for 1 h in vacuum and at 1000 degrees C for 12 h in Ar atmosphere. The single-crystalline structure of the TiN layer is stable up to annealing temperatures of 1000 degrees C as shown by high resolution transmission electron microscopy. While no Cu diffusion was evident after annealing at 900 degrees C, scanning transmission electron microscopy images and energy-dispersive X-ray spectrometry maps show a uniform diffusion layer of about 12 nm after annealing at 1000 degrees C for 12 h. Concentration depth profiles obtained from 3D atom probe tomography reconstructions confirm these findings and reveal that the TiN film is slightly substoichiometric with a N/Ti ratio of 0.92. Considering this composition, we propose a lattice diffusion mechanism of Cu in TiN via the formation of Cu-N vacancy complexes. The excellent diffusion barrier properties of single-crystalline TiN are further attributed to the lack of fast diffusion paths such as grain boundaries.
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| 10. |
- Tamm, Aile, et al.
(author)
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Atomic layer deposition of high-k dielectrics on carbon nanoparticles
- 2013
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In: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 538, s. 16-20
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Journal article (peer-reviewed)abstract
- Carbon nanoparticles were synthesized from 5-methylresorcinol and formaldehyde via base catalysed polycondensation reaction and distributed over silicon oxide wafers and aluminium oxide thin films. These particles essentially possessed monocrystalline graphite structure. The particles were covered by hafnium oxide thin films in metal chloride based atomic layer deposition process carried out at 300 degrees C. Upon deposition of HfO2, thin crystalline metal oxide layer containing mostly cubic phase was formed. At the same time, deposition of the metal oxide caused reduction of the sizes of graphite particles and essential increase in the disorder in carbon.
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