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  • 1.
    Birch, Jens
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties2006Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 514, nr 1-2, s. 10-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single crystal CrN/ScN superlattice films with modulation periods of 1.64 nm were grown on MgO(001) substrates. By utilizing a magnetically enhanced plasma in the vicinity of the substrate and a negative substrate bias, ion/metal nitride flux ratios of 45 and 144 were achieved during deposition of CrN and ScN, respectively. The effects of ion energies in the range [16–58 eV] and substrate temperatures in the range [535–853 °C] on the composition, interface width, crystal quality, and microstructure evolution were investigated using elastic recoil detection analysis, hard X-ray reflectivity, X-ray diffraction, and transmission electron microscopy (TEM). Minimal interface widths of 0.2 nm = 1/2 nitride unit cell were achieved at a growth temperature of 735 °C and ion energies of 24 and 28 eV for CrN and ScN, respectively. Under these conditions, also an optimum in the crystal quality was observed for near stoichiometric composition of CrN and ScN. TEM confirmed a cube-on-cube epitaxial relationship for the system with CrN(001)ScN(001)MgO(001) and CrN[100]ScN[100]MgO[100]. Also, the layers were coherently strained to each other with no misfit dislocations, threading dislocations, surface cusps, voids or gas bubbles present. Higher ion energies or lower deposition temperatures gave over-stoichiometric films with poor superlattice modulation while higher growth temperatures yielded a decreased crystal quality, due to loss of N. As-deposited superlattices with only 61 periods exhibited an absolute soft X-ray reflectance of 6.95% at an energy of 398.8 eV (Sc 2p-absorption edge) which is comparable to the performance of Cr/Sc. The compositional modulation and phase structure was stable during extended annealing at 850 °C, which is the highest thermal stability for an X-ray multilayer mirror. It is concluded that the ScN layers serve as effective diffusion barriers to hinder decomposition of the CrN layers and stabilize the pseudomorphic superlattice structure. Nanoindentation experiments showed that the hardness of the CrN/ScN superlattice films was 19 GPa.

  • 2.
    Eklund, Per
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ljungcrantz, Henrik
    Impact Coatings AB, Linköping, Sweden.
    Wilhelmsson, Ola
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Czigany, Zsolt
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Microstructure and electrical properties of Ti-Si-C-Ag nanocomposite thin films2007Ingår i: Surface and Coatings Technology, ISSN 0257-8972, Vol. 201, nr 14, s. 6465-6469Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti–Si–C–Ag nanocomposite coatings consisting of nanocrystalline TiC in an amorphous Si matrix with segregated Ag were deposited by dual magnetron sputtering from Ti3SiC2 and Ag targets. As evidenced by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, for Ag contents below 10 at.%, the Ag forms 10 nm large crystallites that are homogeneously distributed in the films. For higher Ag contents, coalescence during growth results in the formation of >  100 nm Ag islands on the film surface. The electrical resistivity of the coatings was measured in a four-point-probe setup, and ranged from 340 μΩcm (for Ti–Si–C coatings without Ag) to 40 μΩcm (for high Ag content).

  • 3.
    Hallin, Christer
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Joelsson, Torbjörn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    The effect of thermal gradients on SiC wafers2003Ingår i: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, s. 193-196Konferensbidrag (Refereegranskat)
    Abstract [en]

    An in-situ curvature measurement equipment has been used to measure the curvature change of 4H-SiC 8degrees off-axis wafers, both with and without a CVD grown epitaxial layer, under beat treatments. The curvature of the wafer was found to increase while heating on the back-side and measuring on the front-side. This was independent whether Si- or C-face was towards the heater. The change in curvature was similar to0.05 m(-1) when ramping the temperature from R.T. up to 1300 degreesC, and was slightly more pronounced in the <11 (2) over bar0> direction compared with the <1 (1) over bar 00> direction.

  • 4.
    Högberg, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Emmerlich, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Molina-Aldareguia, Jon M.
    Department of Materials, CEIT, Spain.
    Palmquist, Jens-Petter
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Wilhelmsson, Ola
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Jansson, Ulf
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Growth and characterization of MAX-phase thin films2005Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 193, nr 1-3, s. 6-10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report that magnetron sputtering can be applied to synthesize MAX-phase films of several systems including Ti–Si–C, Ti–Ge–C, Ti–Al–C, and Ti–Al–N. In particular, epitaxial films of the known phases Ti3SiC2, Ti3GeC2, Ti2GeC, Ti3AlC2, Ti2AlC, and Ti2AlN as well as the newly discovered thin film phases Ti4SiC3, Ti4GeC3 and intergrown structures can be deposited at 900–1000 °C on Al2O3(0001) and MgO(111) pre-seeded with TiC or Ti(Al)N. From XTEM and AFM we suggest a growth and nucleation model where MAX-phase nucleation is initiated at surface steps or facets on the seed layer and followed by lateral growth. Differences between the growth behavior of the systems with respect to phase distribution and phase stabilities are discussed. Characterization of mechanical properties for Tin+1Si–Cn films with nanoindentation show decreased hardness from about 25 to 15 GPa upon penetration of the basal planes with characteristic large plastic deformation with pile up dependent on the choice of MAX material. This is explained by cohesive delamination of the basal planes and kink band formation, in agreement with the observations made for bulk material. Measurements of the electrical resistivity for Ti–Si–C and Ti–Al–N films with four-point probe technique show values of 30 and 39 μΩ cm, respectively, comparable to bulk materials.

  • 5.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik och mätteknik. Linköpings universitet, Tekniska högskolan.
    Growth, structure and properties of ternary transition metal nitride thin films prepared by reactive magnetron sputtering2003Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Early transition metal nitrides have found an extensive use in a range of applications. Even though the use is wide there are still large fields to explore. The work in this thesis has been directed towards increasing the fundamental understanding of the synthesis, characterization, and properties for some technologically relevant nitrides. Both binary and ternary phases of transition metal nitrides have been studied. In order to do so pure film materials were achieved by Ultra-High Vacuum Reactive Magnetron Sputtering. Findings from the TiN/TaN system show a correlation between phase composition in TaN and the stress evolution measured in-situ during deposition. It is also shown how the individual layers in a multilayer (thickness ~30 Å) effects the stress with a sub-nm resolution. The contribution from thermal stress is seen and the increase in temperature due to bombardment of energetic particles is calculated from that stress. In the NbxZr1-xN system experiments and calculations on the phase are used to derive a valence electron concentration, corresponding to x = 0.5, for which the films exhibit an enhanced number of stacking faults. This result in an effective hardness increase by 20 % compared to ZrN and NbN. MAX-structured Ti2A1N is synthesized for the first time in the thin film form and a pure single phase epitaxial film is grown on MgO(111) at 830°C. The Ti2A1N is characterized with respect to structure and mechanical properties. The room-temperature resistivity found is 39 µΩcm and the Young's modulus and hardness 210 and 16.1 GPa, respectively.

  • 6.
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nanostructural design of transition metal nitride thin films2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Early transition metal nitrides have found extensive use in a range of thin film applications. We are just beginning to understand their growth from vapor phase deposition and microstructure-property relationships. There are large fields to explore, not the least for the nanoand microstructural design in materials offered by a developed deposition process control and alloying by additional elements to grow, e.g., ternary nitrides or superlattices. The work in this thesis has been directed towards increasing the fondarnental understanding of the synthesis, characterization, and properties for some technologically relevant nitrides. Binary and ternary phases of transition metal nitrides, as well as artificial superlattice structures have been studied. In order to prepare materials of high purity, film deposition was performed by Ultra-High Vacuum Reactive Magnetron Sputtering.

    In this thesis single-crystal Ti2A1N(0001) thin films were synthesized by epitaxial growth onto MgO(111) substrates at elevated temperature and using a 2Ti:A1 compound sputtering target. This is the first thin film deposition process reported for a nitride of the so called Ma+1AXn phase family of compounds - an inherently nanolaminated material that is characterized by metallic conductivity and ductility with retained ceramic strength, high-temperature stability, oxidation, and corrosion resistance. Th2A1N is found to have a room-temperature resistivity of 39 μΩcm, Young's modulus of 16-17 GPa, and hardness of 210 GPa. It is also found that nitrogen-depleted deposition conditions yield the growth of equilibriwn phases TiA1, Ti3A1 and Ti3A1N. For overstoichiometric deposition conditions with respect to Ti2A1N, a phase mixture with TiN was obtained. A super-structure in the TiN phase was also observed to form along the [111] direction at a repetition distance of 7.34 Å, possibly related to A1 segregation.

    CrN/ScN superlattices were designed for use as soft x-ray mirrors and investigated with respect to thermal stability, hardness, and x-ray reflectivity properties. The combined performance of as-deposited superlattices films, with a compositional modulation period of 1.64 nm, both as a mirror and for thermal and mechanical stability was found to be far better than state of the art metallic Cr/Sc multilayers. In fact, the obtained reflectance of 6.95% at a wavelength of 3.1 nm is excellent, the structure is intact after annealing above 800 °C, and the hardness of 19 GPa makes the mirror effectively scratch-proof.

    Stress measurements in the TiN/TaN system were performed in-situ. The obtained results showed that a technique based on curvature measurements by laser deflection on the sample during thin film deposition works when employed at the elevated temperatures typically used for sputtering of nitrides. Findings from the in-situ measurements show a correlation between the stress and the film microstructure and the phase composition of TaN layers. It is also shown how the individual layers in an TiN/TaN artificial superlattice affects the stress with a sub-nm resolution. The contribution from thermal stress is also detected and the fine increase in temperature due to exposure of energetic particles from the plasma can be calculated from that stress.

    A multiphase region in nitrides was demonstrated to form in the NbxZr1-xN model system. The existence of such a multiphase or polytypic structure is predicted by first-principles density functional theory calculations that to occur in nitrides of compositional regions with valence electron concentrations that yield the same total energy for different crystal structures. Films with varying composition were grown and transmission electron microscopy studies revealed an increase in defect density for the x= 0.5 composition. Nanoindentation performed on such films showed an increase in hardness of - 20% compared to the binary nitrides. Analysis of the indents revealed that materials volumes had rotated away from the indenter, thus offering an alternative mechanism for plastic deformation compared to glide on preferred slip systems seen in the cubic binary nitrides. The materials design concept of such phase stability tuning for mechanical strengthening by a high density of phase interfaces is proposed to be expanded to other materials systems.

    Delarbeten
    1. Single-crystal Ti2AlN thin films
    Öppna denna publikation i ny flik eller fönster >>Single-crystal Ti2AlN thin films
    2005 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, nr 11, s. 111913-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We have produced pure thin-film single-crystal Ti2AlN(0001), a member of the Mn+1AXn class of materials. The method used was UHV dc reactive magnetron sputtering from a 2Ti:Al compound target in a mixed Ar–N2 discharge onto (111) oriented MgO substrates. X-ray diffraction and transmission electron microscopy were used to establish the hexagonal crystal structure with c and a lattice parameters of 13.6 and 3.07 Å, respectively. The hardness H, and elastic modulus E, as determined by nanoindentation measurements, were found to be 16.1±1 GPa and 270±20 GPa, respectively. A room-temperature resistivity for the films of 39 μΩ cm was obtained.

    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-45490 (URN)10.1063/1.1882752 (DOI)
    Tillgänglig från: 2009-10-11 Skapad: 2009-10-11 Senast uppdaterad: 2017-12-13
    2. Deposition of single-crystal Ti2AlN thin films by reactive magnetron sputtering from a 2Ti:Al compound target
    Öppna denna publikation i ny flik eller fönster >>Deposition of single-crystal Ti2AlN thin films by reactive magnetron sputtering from a 2Ti:Al compound target
    2007 (Engelska)Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, nr 7, s. 074918-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Single-crystal Ti2AlN (0001) thin films were grown on (111) oriented MgO substrates kept at 830 °C by ultrahigh vacuum dc reactive magnetron sputtering from a compound 2Ti:Al target in a mixed Ar/N2 discharge. The effects of variations in the nitrogen partial pressure on the phase composition of the films were studied. Results from transmission electron microscopy, x-ray diffraction, and elastic recoil detection analysis show a narrow region for growth of Ti2AlN MAX phase with respect to the nitrogen content in the discharge. Perovskite Ti3AlN and intermetallic Ti3Al and TiAl phases dominate at nitrogen depletion. For overstoichiometric deposition conditions with respect to Ti2AlN, a phase mixture with NaCl-structured TiN is obtained. Epitaxial growth is observed with a layer-by-layer mode on the 0001 basal planes for all phases. A superstructure in the TiN phase is also observed along [111] with the repetition distance of 7.34 Å, most likely related to Al segregation. Nanoindentation shows that the film hardness increases from 11 to 27 GPa with increasing nitrogen content and corresponding phase transformations from Ti–Al intermetallics to Ti3AlN, Ti2AlN, and TiN.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-39389 (URN)10.1063/1.2785958 (DOI)48153 (Lokalt ID)48153 (Arkivnummer)48153 (OAI)
    Tillgänglig från: 2009-10-10 Skapad: 2009-10-10 Senast uppdaterad: 2017-12-13
    3. Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties
    Öppna denna publikation i ny flik eller fönster >>Single crystal CrN/ScN superlattice soft X-ray mirrors: epitaxial growth, structure, and properties
    Visa övriga...
    2006 (Engelska)Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 514, nr 1-2, s. 10-19Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Single crystal CrN/ScN superlattice films with modulation periods of 1.64 nm were grown on MgO(001) substrates. By utilizing a magnetically enhanced plasma in the vicinity of the substrate and a negative substrate bias, ion/metal nitride flux ratios of 45 and 144 were achieved during deposition of CrN and ScN, respectively. The effects of ion energies in the range [16–58 eV] and substrate temperatures in the range [535–853 °C] on the composition, interface width, crystal quality, and microstructure evolution were investigated using elastic recoil detection analysis, hard X-ray reflectivity, X-ray diffraction, and transmission electron microscopy (TEM). Minimal interface widths of 0.2 nm = 1/2 nitride unit cell were achieved at a growth temperature of 735 °C and ion energies of 24 and 28 eV for CrN and ScN, respectively. Under these conditions, also an optimum in the crystal quality was observed for near stoichiometric composition of CrN and ScN. TEM confirmed a cube-on-cube epitaxial relationship for the system with CrN(001)ScN(001)MgO(001) and CrN[100]ScN[100]MgO[100]. Also, the layers were coherently strained to each other with no misfit dislocations, threading dislocations, surface cusps, voids or gas bubbles present. Higher ion energies or lower deposition temperatures gave over-stoichiometric films with poor superlattice modulation while higher growth temperatures yielded a decreased crystal quality, due to loss of N. As-deposited superlattices with only 61 periods exhibited an absolute soft X-ray reflectance of 6.95% at an energy of 398.8 eV (Sc 2p-absorption edge) which is comparable to the performance of Cr/Sc. The compositional modulation and phase structure was stable during extended annealing at 850 °C, which is the highest thermal stability for an X-ray multilayer mirror. It is concluded that the ScN layers serve as effective diffusion barriers to hinder decomposition of the CrN layers and stabilize the pseudomorphic superlattice structure. Nanoindentation experiments showed that the hardness of the CrN/ScN superlattice films was 19 GPa.

    Nyckelord
    CrN, ScN, Superlattice, X-ray mirrors, Reactive magnetron sputtering
    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-13065 (URN)10.1016/j.tsf.2006.02.011 (DOI)
    Tillgänglig från: 2008-05-06 Skapad: 2008-05-06 Senast uppdaterad: 2017-12-13
    4. Residual stress formation in multilayered TiN/TaNx coatings during reactive magnetron sputter deposition
    Öppna denna publikation i ny flik eller fönster >>Residual stress formation in multilayered TiN/TaNx coatings during reactive magnetron sputter deposition
    Visa övriga...
    2000 (Engelska)Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 18, nr 6, s. 2884-2889Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Multilayered physical vapor deposited TiN/TaNx coatings were deposited on cemented carbide substrates using a dual target magnetron sputtering system. The coatings were investigated with respect to the influence of nitrogen partial pressure during deposition on the residual stress developed in the coatings. Furthermore, the fracture strength of the material, i.e., the magnitude of the tensile stress that the coating can support without cracking, was evaluated. It was found that, by increasing the nitrogen partial pressure, it is possible to change the stress from compressive to tensile. The highest tensile stress was about 3.6 GPa. Despite this high stress, the coating displayed no cracking. This implies that it is possible to grow TiN/TaNx multilayered coatings with high tensile fracture strength using dual magnetron sputtering and a high deposition temperature (about 680 °C). 

    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-47552 (URN)10.1116/1.1308594 (DOI)
    Tillgänglig från: 2009-10-11 Skapad: 2009-10-11 Senast uppdaterad: 2017-12-13
    5. Stress evolution in TiN and TaN layers and multilayers prepared by reactive magnetron sputtering and studied with in-situ laser reflection curvature technique
    Öppna denna publikation i ny flik eller fönster >>Stress evolution in TiN and TaN layers and multilayers prepared by reactive magnetron sputtering and studied with in-situ laser reflection curvature technique
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Time-resolved in-situ curvature measurements have been used to measure the stress evolution during UHV-based reactive magnetron sputter deposition of TiN and TaN layers and multilayers at 750° C onto Si wafers. It was fmmd that the stress in the initial TiN layers is compressive and reaches a maximum value of -1.2 GPa at 10 nm, there after the stress evolves to tensile during steady state columnar growth. It is suggested that the initial compressive stress is caused by the affinity of reducing any SiO2 to TixSiyOz and the heat transfer from the discharge to the substrate, corresponding to a temperature raise of ~35 °C on the substrate. The stress evolution in TaN layers gwwn on TiN template layers depends strongly on the nitrogen partial pressure in the discharge, from 1 to 3.5 mTorr. This can be correlated with the condition that TaN undergoes phase transformations as the nitrogen partial pressure increase. At low nitrogen content the dominating phase is the hexagonal γ-Ta2N phase and the stress is as high as -1.0 GPa. At higher nitrogen content the layer is essentially stress free with a mixture of cubic δ-TaN and hexagonal ε-TaNphases. This nitrogen dependence combined with the high time sensitivity of the measuring technique provides means to control the stress or phase composition in a given film during growth. It is also shown that the stress evolution in the individual layers in a TiN/faN superlattice with a period as small as 5 nm can be resolved.

    Nationell ämneskategori
    Teknik och teknologier
    Identifikatorer
    urn:nbn:se:liu:diva-85686 (URN)
    Tillgänglig från: 2012-11-28 Skapad: 2012-11-28 Senast uppdaterad: 2016-08-31
    6. Phase stability tuning in the NbxZr1−xN thin-film system for large stacking fault density and enhanced mechanical strength
    Öppna denna publikation i ny flik eller fönster >>Phase stability tuning in the NbxZr1−xN thin-film system for large stacking fault density and enhanced mechanical strength
    2005 (Engelska)Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, nr 13, s. 131922-Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The phase stability of hexagonal WC-structure and cubic NaCl-structure 4d transition metal nitrides was calculated using first-principles density functional theory. It is predicted that there is a multiphase or polytypic region for the 4d transition metal nitrides with a valence electron concentration around 9.5 to 9.7 per formula unit. For verification, epitaxial NbxZr1−xN (0 ⩽ x ⩽ 1) was grown by reactive magnetron sputter deposition on MgO(001) substrates and analyzed with transmission electron microscopy (TEM) and x-ray diffraction. The defects observed in the films were threading dislocations due to nucleation and growth on the lattice-mismatched substrate and planar defects (stacking faults) parallel to the substrate surface. The highest defect density was found at the x = 0.5 composition. The nanoindentation hardness of the films varied between 21 GPa for the binary nitrides, and 26 GPa for Nb0.5Zr0.5N. Unlike the cubic binary nitrides, no slip on the preferred 〈10〉{110} slip system was observed. The increase in hardness is attributed to the increase in defect density at x = 0.5, as the defects act as obstacles for dislocation glide during deformation. The findings present routes for the design of wear-resistant nitride coatings by phase stability tuning.

    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-28403 (URN)10.1063/1.1884743 (DOI)13539 (Lokalt ID)13539 (Arkivnummer)13539 (OAI)
    Tillgänglig från: 2009-10-09 Skapad: 2009-10-09 Senast uppdaterad: 2017-12-13
  • 7.
    Joelsson, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Stress evolution in TiN and TaN layers and multilayers prepared by reactive magnetron sputtering and studied with in-situ laser reflection curvature techniqueManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Time-resolved in-situ curvature measurements have been used to measure the stress evolution during UHV-based reactive magnetron sputter deposition of TiN and TaN layers and multilayers at 750° C onto Si wafers. It was fmmd that the stress in the initial TiN layers is compressive and reaches a maximum value of -1.2 GPa at 10 nm, there after the stress evolves to tensile during steady state columnar growth. It is suggested that the initial compressive stress is caused by the affinity of reducing any SiO2 to TixSiyOz and the heat transfer from the discharge to the substrate, corresponding to a temperature raise of ~35 °C on the substrate. The stress evolution in TaN layers gwwn on TiN template layers depends strongly on the nitrogen partial pressure in the discharge, from 1 to 3.5 mTorr. This can be correlated with the condition that TaN undergoes phase transformations as the nitrogen partial pressure increase. At low nitrogen content the dominating phase is the hexagonal γ-Ta2N phase and the stress is as high as -1.0 GPa. At higher nitrogen content the layer is essentially stress free with a mixture of cubic δ-TaN and hexagonal ε-TaNphases. This nitrogen dependence combined with the high time sensitivity of the measuring technique provides means to control the stress or phase composition in a given film during growth. It is also shown that the stress evolution in the individual layers in a TiN/faN superlattice with a period as small as 5 nm can be resolved.

  • 8.
    Joelsson, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Flink, Axel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Deposition of single-crystal Ti2AlN thin films by reactive magnetron sputtering from a 2Ti:Al compound target2007Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, nr 7, s. 074918-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Single-crystal Ti2AlN (0001) thin films were grown on (111) oriented MgO substrates kept at 830 °C by ultrahigh vacuum dc reactive magnetron sputtering from a compound 2Ti:Al target in a mixed Ar/N2 discharge. The effects of variations in the nitrogen partial pressure on the phase composition of the films were studied. Results from transmission electron microscopy, x-ray diffraction, and elastic recoil detection analysis show a narrow region for growth of Ti2AlN MAX phase with respect to the nitrogen content in the discharge. Perovskite Ti3AlN and intermetallic Ti3Al and TiAl phases dominate at nitrogen depletion. For overstoichiometric deposition conditions with respect to Ti2AlN, a phase mixture with NaCl-structured TiN is obtained. Epitaxial growth is observed with a layer-by-layer mode on the 0001 basal planes for all phases. A superstructure in the TiN phase is also observed along [111] with the repetition distance of 7.34 Å, most likely related to Al segregation. Nanoindentation shows that the film hardness increases from 11 to 27 GPa with increasing nitrogen content and corresponding phase transformations from Ti–Al intermetallics to Ti3AlN, Ti2AlN, and TiN.

  • 9.
    Joelsson, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hugosson, Håkan
    Condensed Matter Theory Group, Department of Physics, Uppsala University, Uppsala, Sweden.
    Molina-Aldareguia, Jon M.
    CEIT (Centro de Estudios e Investigaciones Técnicas de Gipuzkoa), San Sebastian, Spain .
    Phase stability tuning in the NbxZr1−xN thin-film system for large stacking fault density and enhanced mechanical strength2005Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, nr 13, s. 131922-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The phase stability of hexagonal WC-structure and cubic NaCl-structure 4d transition metal nitrides was calculated using first-principles density functional theory. It is predicted that there is a multiphase or polytypic region for the 4d transition metal nitrides with a valence electron concentration around 9.5 to 9.7 per formula unit. For verification, epitaxial NbxZr1−xN (0 ⩽ x ⩽ 1) was grown by reactive magnetron sputter deposition on MgO(001) substrates and analyzed with transmission electron microscopy (TEM) and x-ray diffraction. The defects observed in the films were threading dislocations due to nucleation and growth on the lattice-mismatched substrate and planar defects (stacking faults) parallel to the substrate surface. The highest defect density was found at the x = 0.5 composition. The nanoindentation hardness of the films varied between 21 GPa for the binary nitrides, and 26 GPa for Nb0.5Zr0.5N. Unlike the cubic binary nitrides, no slip on the preferred 〈10〉{110} slip system was observed. The increase in hardness is attributed to the increase in defect density at x = 0.5, as the defects act as obstacles for dislocation glide during deformation. The findings present routes for the design of wear-resistant nitride coatings by phase stability tuning.

  • 10.
    Joelsson, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hörling, Anders
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Single-crystal Ti2AlN thin films2005Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 86, nr 11, s. 111913-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have produced pure thin-film single-crystal Ti2AlN(0001), a member of the Mn+1AXn class of materials. The method used was UHV dc reactive magnetron sputtering from a 2Ti:Al compound target in a mixed Ar–N2 discharge onto (111) oriented MgO substrates. X-ray diffraction and transmission electron microscopy were used to establish the hexagonal crystal structure with c and a lattice parameters of 13.6 and 3.07 Å, respectively. The hardness H, and elastic modulus E, as determined by nanoindentation measurements, were found to be 16.1±1 GPa and 270±20 GPa, respectively. A room-temperature resistivity for the films of 39 μΩ cm was obtained.

  • 11.
    Molina-Aldareguia, J.M.
    et al.
    Dept. of Mat. Sci. and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, United Kingdom.
    Lloyd, S.J.
    Dept. of Mat. Sci. and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, United Kingdom.
    Odén, Magnus
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material.
    Joelsson, Torbjörn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Clegg, W.J.
    Dept. of Mat. Sci. and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ, United Kingdom.
    Deformation structures under indentations in TiN/NbN single-crystal multilayers deposited by magnetron sputtering at different bombarding ion energies2002Ingår i: Philosophical magazine. A. Physics of condensed matter. Defects and mechanical properties, ISSN 0141-8610, Vol. 82, nr 10 SPEC., s. 1983-1992Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Work elsewhere has suggested that multilayer films with layer thicknesses of a few nanometres can be much harder than monolithic films, although there is considerable variation in the observed magnitude of this effect. To investigate this, multilayer TiN/NbN films have been deposited by reactive magnetron sputtering on to MgO single crystals. The hardnesses measured were similar to those of the TiN and NbN alone, which is consistent with the observation by transmission electron microscopy (TEM) that deformation across the interfaces was not prevented. Varying the electrical potential at which the film was grown from -10 to -200 V and the corresponding ion energy from 10 to 200 eV increased the hardness from 19 to 25 GPa, further decreases in the potential caused the hardness to decrease. Using TEM, deformation was observed to occur along the apparent columnar boundaries within the films, suggesting that the effect of the electrical potential on the measured hardness was caused by changes in the apparent strength of the columnar boundaries, possibly associated with the variations in the volume fraction of voids that were observed on these boundaries.

  • 12.
    Nordin, M.
    et al.
    AB Sandvik Coromant, Stockholm, Sweden .
    Larsson, M.
    Materials Science Division, The Ångström Laboratory, Uppsala University, Uppsala, Sweden .
    Joelsson, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Residual stress formation in multilayered TiN/TaNx coatings during reactive magnetron sputter deposition2000Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 18, nr 6, s. 2884-2889Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multilayered physical vapor deposited TiN/TaNx coatings were deposited on cemented carbide substrates using a dual target magnetron sputtering system. The coatings were investigated with respect to the influence of nitrogen partial pressure during deposition on the residual stress developed in the coatings. Furthermore, the fracture strength of the material, i.e., the magnitude of the tensile stress that the coating can support without cracking, was evaluated. It was found that, by increasing the nitrogen partial pressure, it is possible to change the stress from compressive to tensile. The highest tensile stress was about 3.6 GPa. Despite this high stress, the coating displayed no cracking. This implies that it is possible to grow TiN/TaNx multilayered coatings with high tensile fracture strength using dual magnetron sputtering and a high deposition temperature (about 680 °C). 

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