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Reactive Sputtering of Complex Multi-component Nitride Thin Films
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. (Oorganisk kemi)ORCID iD: 0000-0001-7266-0022
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The ever-increasing demand on improvement of protective nitride thin films has led to an expansion of the research field into multi-element based materials. The work in this thesis has focused on exploring new complex, multi-component nitride thin films based on three different material systems: Al-Ge-N, Hf-Nb-Ti-V-Zr-N and Al-Cr-Nb-Y-Zr-N. All films were synthesised by reactive dc magnetron sputtering and characterised with regard to structure and material properties, in particular the mechanical, optical and corrosion properties.

The Al-Ge-O-N coatings exhibited amorphisation of the structure upon oxygen addition, via the formation of a crystalline (Al1-xGex)(N1-yOy) solid solution phase for low O contents. The mechanical properties were improved, and hardness values up to 29 GPa were achieved for low O and Ge concentrations, most likely due to nanocomposite hardening. The optical absorption edge was tuneable towards shorter and longer wavelengths with increasing the O and Ge content respectively. Annealing to 850°C showed indications of increased thermal stability for the quaternary Al-Ge-O-N films compared to the ternary Al-Ge-N films.

Coatings in the Hf-Nb-Ti-V-Zr-N system were found to be highly crystalline featuring a single solid solution phase with NaCl-type structure for low Hf content, whereas an additional, tetragonally distorted, phase appeared for higher Hf contents. The mechanical properties, such as hardness and Young’s modulus increased with increasing Hf content, although the values were relatively low compared to those for transition metal nitrides in general.

The Al-Cr-Nb-Y-Zr-N films also crystallised in the NaCl-type structure for the films with high nitrogen contents, i.e. between 46 and 51 at.%. However, partial elemental segregation was present, mainly for yttrium, both within the grains and in the column boundaries. XPS results suggested that yttrium was in a metallic state, while the remaining elements were present in a nitrided environment. The partial segregation could possibly explain the observed ductile behaviour of the nitride films. Electrochemical tests showed that the corrosion resistance increased with increased nitrogen content and the films performed in some cases better than a hyper-duplex stainless steel.

This thesis demonstrates that solid solutions are formed for three relatively different nitride material systems when varying the composition. The solubilities of the solid solution phases were found to be limited as shown by amorphisation, partial elemental segregation or formation of a two-phase material. The limited solubility and the phase changes can be used to design the material properties.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. , p. 71
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1852
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-392704ISBN: 978-91-513-0744-2 (print)OAI: oai:DiVA.org:uu-392704DiVA, id: diva2:1349301
Public defence
2019-10-25, Polhemssalen, Ångströmslaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2019-10-04 Created: 2019-09-08 Last updated: 2019-10-15
List of papers
1. Influence of oxygen content on structure and material properties of reactively sputtered Al-Ge-O-N thin films
Open this publication in new window or tab >>Influence of oxygen content on structure and material properties of reactively sputtered Al-Ge-O-N thin films
2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 738, p. 515-527Article in journal (Refereed) Published
Abstract [en]

Ternary Al-Ge-N and quaternary Al-Ge-O-N coatings were deposited by reactive dc magnetron cosputtering of Al and Ge targets in an Ar/N-2 or Ar/N-2/O-2 atmosphere at a substrate temperature of 250 degrees C. The structure and material properties of the coatings were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nanoindentation, UV-vis spectroscopy and optical profilometry. In agreement with literature, the ternary Al-Ge-N coatings were found to be nanocomposite materials with nanocrystalline (Al1-xGex) N-y solid solution phase in a Ge3N4-z amorphous matrix. The Al-Ge-O-N coatings consisted of a nanocrystalline wurzite-type (Al1-xGex)( N1-yOy) solid solution phase for low oxygen concentrations with a possible co-existence of an amorphous Ge-N matrix phase. For higher O contents, the coatings became X-ray amorphous. The mechanical properties of the Al-Ge-O-N films were improved for low oxygen content, as compared to the ternary Al-Ge-N samples, showing an increase in hardness up to 29 GPa and Young's modulus to 320 GPa. The oxygen addition also resulted in an additional design parameter of the optical properties compared to the ternary Al-Ge-N films. The optical absorption edge was thus tuneable towards both shorter and longer wavelength by changing the O and Ge content respectively, and ranged from 302 to 373 nm, corresponding to an optical bandgap (E-04) between 4.1 and 3.3 eV. After annealing of the Al-Ge-O-N coatings in ultra-high vacuum at 500 degrees C, indications of increased thermal stability for the coating with high oxygen content were observed. For the annealed Al-Ge-O-N films the mechanical properties were improved upon heat treatment, while the optical properties were only slightly changed. These results suggests that coatings of the Al-Ge-O-N system could be suitable as protective optical coatings at elevated temperatures.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Reactive sputtering, Al-Ge-O-N, Optical properties, Hard coatings, Thermal stability
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-341556 (URN)10.1016/j.jallcom.2017.12.185 (DOI)000419214800062 ()
Funder
Swedish Research Council, C0514401Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2018-02-13 Created: 2018-02-13 Last updated: 2019-09-08Bibliographically approved
2. In Situ Formation of Ge Nanoparticles by Annealing of Al-Ge‑N ThinFilms Followed by HAXPES and XRD
Open this publication in new window or tab >>In Situ Formation of Ge Nanoparticles by Annealing of Al-Ge‑N ThinFilms Followed by HAXPES and XRD
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2019 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 58, no 16, p. 11100-11109Article in journal (Refereed) Published
Abstract [en]

Ge nanoparticles embedded in thin films have attracted a lot of attention due to their promising optical and electronic properties that can be tuned by varying the particle size and choice of matrix material. In this study, Ge nanoparticle formation was investigated for Al-Ge-N based thin films by simultaneous measurements of HAXPES and grazing incidence XRD during in situ annealing in vacuum conditions. As-deposited Al-Ge-N thin films, synthesized by reactive dc magnetron sputtering, consisted of a nanocrystalline (Al1–xGex)Ny solid solution and an amorphous tissue phase of Ge3Ny. Upon annealing to 750 °C, elemental Ge was formed shown by both HAXPES and XRD measurements, and N2 gas was released as measured by a mass spectrometer. Postannealed ex situ analysis by SEM and TEM showed that the elemental Ge phase formed spherical nanoparticles on the surface of the film, with an average size of 210 nm. As the annealing temperature increased further to 850 °C, the Ge particles on the film surface evaporated, while the phase segregation of Ge still could be observed within the film. Thus, these results show the possibility for a controlled synthesis of Ge nanoparticles through annealing of Al-Ge-N thin films to produce materials suitable for use in electronic or optoelectronic devices.

National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392698 (URN)10.1021/acs.inorgchem.9b01631 (DOI)000482173300075 ()31381309 (PubMedID)
Funder
Swedish Research Council, 2014-6463EU, FP7, Seventh Framework Programme, INCA 600398
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-10-08Bibliographically approved
3. Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition
Open this publication in new window or tab >>Multicomponent Hf-Nb-Ti-V-Zr nitride coatings by reactive magnetron sputter deposition
2018 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 349, p. 529-539Article in journal (Refereed) Published
Abstract [en]

Multicomponent nitride coatings of the Hf-Nb-Ti-V-Zr system with different Hf content (0-18 at.%) were deposited using reactive dc magnetron sputtering. Coatings with lower Hf content (0-7 at.%) were found to consist of a single solid solution phase with NaCl-type structure (space group Fm-3m). Coatings with higher Hf content (10-18 at.%) showed a two-phase material consisting of cubic Fm-3m and tetragonal I4/m:run solid solution phase. The lattice distortion, estimated by calculating the delta-parameter under the assumption of a single solid solution phase, varied between 3.8 and 4.0% and slightly decreased with increasing Hf content. SEM and TEM cross section images showed a columnar microstructure with columns that were frayed on the surface or throughout the whole column. The column size decreased as Hf content increased. The hardness increased from 8 to 19 GPa with increased Hf content, which most probably is related to the change in microstructure rather than change in lattice distortion. The electrical resistivity for all samples ranged between 231 and 286 mu Omega cm.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Multiprincipal element nitride, High-entropy nitride, Two-phase nitride, Transition metal nitride, Tetragonal distortion, Thin films
National Category
Materials Chemistry Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:uu:diva-362098 (URN)10.1016/j.surfcoat.2018.06.030 (DOI)000441492600056 ()
Funder
Swedish Research Council, C0514401Swedish Foundation for Strategic Research , RIF14-0053
Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2019-09-08Bibliographically approved
4. Multi-component (Al,Cr,Nb,Y,Zr)N thin films by reactive magnetron sputter deposition for increased hardness and corrosion resistance
Open this publication in new window or tab >>Multi-component (Al,Cr,Nb,Y,Zr)N thin films by reactive magnetron sputter deposition for increased hardness and corrosion resistance
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(English)Manuscript (preprint) (Other academic)
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392700 (URN)
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-09-11
5. Influence of N content on structure and mechanical properties of multi-component Al-Cr-Nb-Y-Zr based thin films by reactive magnetron sputtering
Open this publication in new window or tab >>Influence of N content on structure and mechanical properties of multi-component Al-Cr-Nb-Y-Zr based thin films by reactive magnetron sputtering
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(English)Manuscript (preprint) (Other academic)
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392701 (URN)
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-09-08
6. Corrosion in Al-Cr-Nb-Y-Zr-N multi-component alloys: What role does the nitrogen content play?
Open this publication in new window or tab >>Corrosion in Al-Cr-Nb-Y-Zr-N multi-component alloys: What role does the nitrogen content play?
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(English)Manuscript (preprint) (Other academic)
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-392702 (URN)
Available from: 2019-09-08 Created: 2019-09-08 Last updated: 2019-09-11

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