| 1. |
- Dahlqvist, Martin, et al.
(författare)
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Out-Of-Plane Ordered Laminate Borides and Their 2D Ti-Based Derivative from Chemical Exfoliation
- 2021
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Ingår i: Advanced Materials. - : Wiley-VCH Verlagsgesellschaft. - 0935-9648 .- 1521-4095. ; 33:38
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Tidskriftsartikel (refereegranskat)abstract
- Exploratory theoretical predictions in uncharted structural and compositional space are integral to materials discoveries. Inspired by M5SiB2 (T2) phases, the finding of a family of laminated quaternary metal borides, M M-4 SiB2, with out-of-plane chemical order is reported here. 11 chemically ordered phases as well as 40 solid solutions, introducing four elements previously not observed in these borides are predicted. The predictions are experimentally verified for Ti4MoSiB2, establishing Ti as part of the T2 boride compositional space. Chemical exfoliation of Ti4MoSiB2 and select removal of Si and MoB2 sub-layers is validated by derivation of a 2D material, TiOxCly, of high yield and in the form of delaminated sheets. These sheets have an experimentally determined direct band gap of approximate to 4.1 eV, and display characteristics suitable for supercapacitor applications. The results take the concept of chemical exfoliation beyond currently available 2D materials, and expands the envelope of 3D and 2D candidates, and their applications.
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| 2. |
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| 3. |
- Gogova, Daniela, et al.
(författare)
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Epitaxial growth of β -Ga 2 O 3 by hot-wall MOCVD
- 2022
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 12:5, s. 055022-055022
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Tidskriftsartikel (refereegranskat)abstract
- The hot-wall metalorganic chemical vapor deposition (MOCVD) concept, previously shown to enable superior material quality and highperformance devices based on wide bandgap semiconductors, such as Ga(Al)N and SiC, has been applied to the epitaxial growth ofβ-Ga2O3. Epitaxial β-Ga2O3 layers at high growth rates (above 1 μm/h), at low reagent flows, and at reduced growth temperatures(740 ○C) are demonstrated. A high crystalline quality epitaxial material on a c-plane sapphire substrate is attained as corroborated by a combination of x-ray diffraction, high-resolution scanning transmission electron microscopy, and spectroscopic ellipsometry measurements. Thehot-wall MOCVD process is transferred to homoepitaxy, and single-crystalline homoepitaxial β-Ga2O3 layers are demonstrated with a 201 ¯rocking curve width of 118 arc sec, which is comparable to those of the edge-defined film-fed grown (201) ¯ β-Ga2O3 substrates, indicative ofsimilar dislocation densities for epilayers and substrates. Hence, hot-wall MOCVD is proposed as a prospective growth method to be furtherexplored for the fabrication of β-Ga2O3
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| 4. |
- Gustafsson, Anders, et al.
(författare)
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Cathodoluminescence investigations of dark-line defects in platelet-based InGaN nano-LED structures
- 2024
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Ingår i: Nanotechnology. - : IOP Publishing Ltd. - 0957-4484 .- 1361-6528. ; 35:25
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the optical properties of heterostructured InGaN platelets aiming at red emission, intended for use as nano-scaled light-emitting diodes. The focus is on the presence of non-radiative emission in the form of dark line defects. We have performed the study using hyperspectral cathodoluminescence imaging. The platelets were grown on a template consisting of InGaN pyramids, flattened by chemical mechanical polishing. These templates are defect free, whereas the dark line defects are introduced in the lower barrier and tend to propagate through all the subsequent layers, as revealed by the imaging of different layers in the structure. We conclude that the dark line defects are caused by stacking mismatch boundaries introduced by multiple seeding and step bunching at the edges of the as-polished, dome shaped templates. To avoid these defects, we suggest that the starting material must be flat rather than dome shaped.
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| 5. |
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| 6. |
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| 7. |
- Knight, Sean Robert, et al.
(författare)
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Room temperature two-dimensional electron gas scattering time, effective mass, and mobility parameters in AlxGa1−xN/GaN heterostructures (0.07 ≤ x ≤ 0.42)
- 2023
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Ingår i: Journal of Applied Physics. - : American Institute of Physics Inc.. - 0021-8979 .- 1089-7550. ; 134:18
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Tidskriftsartikel (refereegranskat)abstract
- Al xGa 1−xN/GaN high-electron-mobility transistor (HEMT) structures are key components in electronic devices operating at gigahertz or higher frequencies. In order to optimize such HEMT structures, understanding their electronic response at high frequencies and room temperature is required. Here, we present a study of the room temperature free charge carrier properties of the two-dimensional electron gas (2DEG) in HEMT structures with varying Al content in the Al xGa 1−xN barrier layers between x=0.07 and x=0.42. We discuss and compare 2DEG sheet density, mobility, effective mass, sheet resistance, and scattering times, which are determined by theoretical calculations, contactless Hall effect, capacitance-voltage, Eddy current, and cavity-enhanced terahertz optical Hall effect (THz-OHE) measurements using a low-field permanent magnet (0.6 T). From our THz-OHE results, we observe that the measured mobility reduction from x=0.13 to x=0.42 is driven by the decrease in 2DEG scattering time, and not the change in effective mass. For x<0.42, the 2DEG effective mass is found to be larger than for electrons in bulk GaN, which in turn, contributes to a decrease in the principally achievable mobility. From our theoretical calculations, we find that values close to 0.3 m0 can be explained by the combined effects of conduction band nonparabolicity, polarons, and hybridization of the electron wavefunction through penetration into the barrier layer.
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| 8. |
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| 9. |
- Lu, Jun, 1962-, et al.
(författare)
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Tin+1Cn MXenes with fully saturated and thermally stable Cl terminations
- 2019
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 1:9, s. 3680-3685
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Tidskriftsartikel (refereegranskat)abstract
- MXenes are a rapidly growing family of 2D materials that exhibit a highly versatile structure and composition, allowing for significant tuning of the materials properties. These properties are, however, ultimately limited by the surface terminations, which are typically a mixture of species, including F and O that are inherent to the MXene processing. Other and robust terminations are lacking. Here, we apply high-resolution scanning transmission electron microscopy (STEM), corresponding image simulations and first-principles calculations to investigate the surface terminations on MXenes synthesized from MAX phases through Lewis acidic melts. The results show that atomic Cl terminates the synthesized MXenes, with mere residual presence of other termination species. Furthermore, in situ STEM-electron energy loss spectroscopy (EELS) heating experiments show that the Cl terminations are stable up to 750 degrees C. Thus, we present an attractive new termination that widely expands the MXenes functionalization space and enables new applications.
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| 10. |
- Palisaitis, Justinas, 1983-, et al.
(författare)
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On the Structural Stability of MXene and the Role of Transition Metal Adatoms
- 2018
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 10:23, s. 10850-10855
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Tidskriftsartikel (refereegranskat)abstract
- In the present communication, the atomic structure and coordination of surface adsorbed species on Nb2C MXene is investigated over time. In particular, the influence of the Nb adatoms on the structural stability and oxidation behavior of the MXene is addressed. This investigation is based on plan-view geometry observations of single Nb2C MXene sheets by a combination of atomic-resolution scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS) and STEM image simulations.
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| 11. |
- Papamichail, A., et al.
(författare)
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Compositionally graded channel HEMTs towards improved linearity for low-noise RF amplifiers
- 2022
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Ingår i: 2022 Compound Semiconductor Week, CSW 2022.
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Konferensbidrag (refereegranskat)abstract
- Although AlGaN/GaN HEMTs with high power and current gain have been demonstrated in RF device applications, at high signal operation they show an inherent non-linear behavior which leads to gain compression and signal distortion. Polarization-doped AlGaN/GaN HEMTs, with a compositionally graded channel enables a linear response improvement through formation of a 3-D electron gas. In this work, we develop the growth process for graded channel HEMTs in a hot-wall MOCVD reactor. Control of the grading profile is established through growth parameter tuning. Afterwards, analysis by EDS allows for precise determination of Al composition across the channel. Conventional and graded channel HEMT structures were fabricated and characterized. Furthermore, the sheet resistance, carrier density and mobility in HEMT structures with different grading profiles are compared and discussed. The conventional (non-graded) structure revealed the highest electron mobility of ~2350 cm2/V.s, which is among the highest values reported.
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| 12. |
- Papamichail, Alexis, et al.
(författare)
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Mg-doping and free-hole properties of hot-wall MOCVD GaN
- 2022
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 131:18
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Tidskriftsartikel (refereegranskat)abstract
- The hot-wall metal-organic chemical vapor deposition (MOCVD), previously shown to enable superior III-nitride material quality and high performance devices, has been explored for Mg doping of GaN. We have investigated the Mg incorporation in a wide doping range (2.45 × 10 18 cm-3 up to 1.10 × 10 20 cm-3) and demonstrate GaN:Mg with low background impurity concentrations under optimized growth conditions. Dopant and impurity levels are discussed in view of Ga supersaturation, which provides a unified concept to explain the complexity of growth conditions impact on Mg acceptor incorporation and compensation. The results are analyzed in relation to the extended defects, revealed by scanning transmission electron microscopy, x-ray diffraction, and surface morphology, and in correlation with the electrical properties obtained by Hall effect and capacitance-voltage (C-V) measurements. This allows to establish a comprehensive picture of GaN:Mg growth by hot-wall MOCVD providing guidance for growth parameters optimization depending on the targeted application. We show that substantially lower H concentration as compared to Mg acceptors can be achieved in GaN:Mg without any in situ or post-growth annealing resulting in p-type conductivity in as-grown material. State-of-the-art p-GaN layers with a low resistivity and a high free-hole density (0.77 ω cm and 8.4 × 10 17 cm - 3, respectively) are obtained after post-growth annealing demonstrating the viability of hot-wall MOCVD for growth of power electronic device structures.
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| 13. |
- Persson, Axel, et al.
(författare)
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Mg segregation at inclined facets of pyramidal inversion domains in GaN:Mg
- 2022
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Ingår i: Scientific Reports. - : Nature Portfolio. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Structural defects in Mg-doped GaN were analyzed using high-resolution scanning transmission electron microscopy combined with electron energy loss spectroscopy. The defects, in the shape of inverted pyramids, appear at high concentrations of incorporated Mg, which also lead to a reduction in free-hole concentration in Mg doped GaN. Detailed analysis pinpoints the arrangement of atoms in and around the defects and verify the presence of a well-defined layer of Mg at all facets, including the inclined facets. Our observations have resulted in a model of the pyramid-shaped defect, including structural displacements and compositional replacements, which is verified by image simulations. Finally, the total concentration of Mg atoms bound to these defects were evaluated, enabling a correlation between inactive and defect-bound dopants.
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| 14. |
- Persson, P. O.Å., et al.
(författare)
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Tuning composition in graded AlGaN channel HEMTs toward improved linearity for low-noise radio-frequency amplifiers
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 122:15
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Tidskriftsartikel (refereegranskat)abstract
- Compositionally graded channel AlGaN/GaN high electron mobility transistors (HEMTs) offer a promising route to improve device linearity, which is necessary for low-noise radio-frequency amplifiers. In this work, we demonstrate different grading profiles of a 10-nm-thick AlxGa1-xN channel from x = 0 to x = 0.1 using hot-wall metal-organic chemical vapor deposition (MOCVD). The growth process is developed by optimizing the channel grading and the channel-to-barrier transition. For this purpose, the Al-profiles and the interface sharpness, as determined from scanning transmission electron microscopy combined with energy-dispersive x-ray spectroscopy, are correlated with specific MOCVD process parameters. The results are linked to the channel properties (electron density, electron mobility, and sheet resistance) obtained by contactless Hall and terahertz optical Hall effect measurements coupled with simulations from solving self-consistently Poisson and Schrödinger equations. The impact of incorporating a thin AlN interlayer between the graded channel and the barrier layer on the HEMT properties is investigated and discussed. The optimized graded channel HEMT structure is found to have similarly high electron density (∼9 × 10 12 cm-2) as the non-graded conventional structure, though the mobility drops from ∼ 2360 cm2/V s in the conventional to ∼ 960 cm2/V s in the graded structure. The transconductance gm of the linearly graded channel HEMTs is shown to be flatter with smaller g m ′ and g m ″ as compared to the conventional non-graded channel HEMT implying improved device linearity.
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| 15. |
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| 16. |
- Zhou, Jie, et al.
(författare)
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High-Entropy Laminate Metal Carbide (MAX Phase) and Its Two-Dimensional Derivative MXene
- 2022
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 34:5, s. 2098-2106
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Tidskriftsartikel (refereegranskat)abstract
- High-entropy (HE) ceramics, by analogy with HE metallic alloys, are an emerging family of multielemental solid solutions. These materials offer a large compositional space, with a corresponding large range of properties. Here, we report the experimental realization of a 3D HE MAX phase, Ti1,0V0.7Cr0.05Nb1.0Ta1.0AlC3, and a corresponding 2D HE MXene in the form of freestanding flakes of average composition Ti1.1V0.7CrxNb1.0Ta0.6C3Tz (T-z = -F, -O, -OH), as produced by selective removal of AI from the HE MAX phase in aqueous hydrofluoric acid (HF). Initial tests on HE MXene "paper" electrodes show their high potential as electrode materials in supercapacitors through volumetric and gravimetric capacitances of 1688 F/cm(3) and 490 F/g, respectively, originating from a combination of diffusion- and surface-controlled charge storage processes. The introduction of the HE concept into the field of 2D materials suggests a wealth of future 2D materials and applications.
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| 17. |
- Alami, Jones, et al.
(författare)
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Ion-assisted Physical Vapor Deposition for enhanced film properties on non-flat surfaces
- 2005
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 23:2, s. 278-280
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Tidskriftsartikel (refereegranskat)abstract
- We have synthesized Ta thin films on Si substrates placed along a wall of a 2-cm-deep and 1-cm-wide trench, using both a mostly neutral Ta flux by conventional dc magnetron sputtering (dcMS) and a mostly ionized Ta flux by high-power pulsed magnetron sputtering (HPPMS). Structure of the grown films was evaluated by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The Ta thin film grown by HPPMS has a smooth surface and a dense crystalline structure with grains oriented perpendicular to the substrate surface, whereas the film grown by dcMS exhibits a rough surface, pores between the grains, and an inclined columnar structure. The improved homogeneity achieved by HPPMS is a direct consequence of the high ion fraction of sputtered species.
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| 18. |
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| 19. |
- Amloy, Supaluck, et al.
(författare)
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Excitons and biexcitons in InGaN quantum dot like localization centers
- 2014
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 25:49, s. 495702-
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Tidskriftsartikel (refereegranskat)abstract
- Indium segregation in a narrow InGaN single quantum well creates quantum dot (QD) like exciton localization centers. Cross-section transmission electron microscopy reveals varying shapes and lateral sizes in the range ∼1–5 nm of the QD-like features, while scanning near field optical microscopy demonstrates a highly inhomogeneous spatial distribution of optically active individual localization centers. Microphotoluminescence spectroscopy confirms the spectrally inhomogeneous distribution of localization centers, in which the exciton and the biexciton related emissions from single centers of varying geometry could be identified by means of excitation power dependencies. Interestingly, the biexciton binding energy (Ebxx) was found to vary from center to center, between 3 to −22 meV, in correlation with the exciton emission energy. Negative binding energies are only justified by a three-dimensional quantum confinement, which confirms QD-like properties of the localization centers. The observed energy correlation is proposed to be understood as variations of the lateral extension of the confinement potential, which would yield smaller values of Ebxx for reduced lateral extension and higher exciton emission energy. The proposed relation between lateral extension and Ebxx is further supported by the exciton and the biexciton recombination lifetimes of a single QD, which suggest a lateral extension of merely ∼3 nm for a QD with strongly negative Ebxx = −15.5 meV.
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| 20. |
- Bakhit, Babak, 1983-, et al.
(författare)
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Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films
- 2021
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Ingår i: Scripta Materialia. - : Elsevier. - 1359-6462 .- 1872-8456. ; 191, s. 120-125
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Tidskriftsartikel (refereegranskat)abstract
- We recently showed that sputter-deposited Zr1-xTaxBy thin films have hexagonal AlB2-type columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. As-deposited layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we study the mechanical properties of ZrB2.4, Zr0.8Ta0.2B1.8, and Zr0.7Ta0.3B1.5 films annealed in Ar atmosphere as a function of annealing temperature Ta up to 1200 °C. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.
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| 21. |
- Bakhit, Babak, 1983-, et al.
(författare)
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Self-organized columnar Zr0.7Ta0.3B1.5 core/shell-nanostructure thin films
- 2020
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 401
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Tidskriftsartikel (refereegranskat)abstract
- We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter-deposited columnar Zr0.7Ta0.3B1.5 thin films. The columns, 95 ± 17 Å, are core/shell nanostructures in which 80 ± 15-Å cores are crystalline hexagonal-AlB2-structure Zr-rich stoichiometric Zr1−xTaxB2. The shell structure is a narrow dense, disordered region that is Ta-rich and highly B-deficient. The cores are formed under intense ion mixing via preferential Ta segregation, due to the lower formation enthalpy of TaB2 than ZrB2, in response to the chemical driving force to form a stoichiometric compound. The films with unique combination of nanosized crystalline cores and dense metallic-glass-like shells provide excellent mechanical properties.
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| 22. |
- Bangolla, Hemanth Kumar, et al.
(författare)
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Composition-dependent photoconductivities in indium aluminium nitride nanorods grown by magnetron sputter epitaxy
- 2022
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Ingår i: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 4:22, s. 4886-4894
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Tidskriftsartikel (refereegranskat)abstract
- Photoconduction (PC) properties were investigated for ternary indium aluminium nitride (InxAl1-xN) nanorods (NRs) with different indium compositions (x) from 0.35 to 0.68, as grown by direct-current reactive magnetron sputter epitaxy. Cross-sectional scanning transmission electron microscopy (STEM) reveals single-crystal quality of the vertically aligned InxAl1-xN NRs. Single-rod photodetector devices with good ohmic contacts were fabricated using the focused-ion-beam technique (FIB), where the In-rich In0.68Al0.32N NR exhibits an optimal photocurrent responsivity of 1400 A W-1 and photoconductive gain of 3300. A transition from a positive photoresponse to a negative photoresponse was observed, while increasing the In composition x from 0.35 to 0.57. The negative PC was further enhanced by increasing x to 0.68. A model based on the coexistence and competition of deep electron trap states and recombination centers was proposed to explain the interesting composition-dependent PC in these ternary III-nitride 1D nanostructures.
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| 23. |
- Beckers, Manfred, et al.
(författare)
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The influence of substrate temperature and Al mobility on the microstructural evolution of magnetron sputtered ternary Ti-Al-N thin films
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 106:6, s. 064915-
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Tidskriftsartikel (refereegranskat)abstract
- Ternary Ti-Al-N films were deposited onto Al2O3 (0001) substrates by reactive co‑sputtering from elemental Ti and Al targets and analyzed by in situ and ex situ x-ray scattering, Rutherford backscattering spectroscopy, transmission electron microscopy and x-ray photoemission spectroscopy. The deposition parameters were set to values that yield Ti:Al:N ratios of 2:1:1 and 4:1:3 at room temperature. 2TiAlN depositions at 675 °C result in epitaxial Ti2AlN growth with basal planes parallel to the substrate surface. Nominal 4TiAl3N depositions at 675 °C and above, however, yield TiN and Ti2AlN domains due to Al loss to the vacuum. Depositions at a lower temperature of 600 °C yield films with correct 4:1:3 stoichiometry, but Ti4AlN3 formation is supposedly prevented by insufficient adatom mobility. Instead, an incoherent Tin+1AlNn structure with random twinned stacking sequences n is obtained, that exhibits both basal plane orientations parallel as well as nearly perpendicular to the substrate interface. X‑ray photoemission spectroscopy shows that in contrast to stoichiometric nitrides the Al is metallically bonded and hence acts as twinning plane within the Tin+1AlNn stackings. Domains with perpendicular basal plane orientation overgrowth those with parallel ones in a competitive growth mode. The resulting morphology is a combination of smooth‑surfaced parallel basal plane orientation domains interrupted by repeated facetted hillock-like features with perpendicular basal plane orientation.
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| 24. |
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| 25. |
- Boström, Mathias, et al.
(författare)
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Atmospheric water droplets can catalyse atom pair break-up via surface-induced resonance repulsion
- 2013
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 101:4, s. 43002-
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Tidskriftsartikel (refereegranskat)abstract
- We present the theory for a retarded resonance interaction between two identical atoms near a dielectric surface. In free space the resonance interaction between isotropically excited atom pairs is attractive at all atom-atom separations. We illustrate numerically how this interaction between oxygen, sulphur, hydrogen, or nitrogen atom pairs may turn repulsive near water droplets. The results provide evidence of a mechanism causing excited state atom pair breakage to occur in the atmosphere near water droplets.
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| 26. |
- Boström, Mathias, et al.
(författare)
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Casimir attractive-repulsive transition in MEMS
- 2012
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Ingår i: European Physical Journal B. - : Springer Science and Business Media LLC. - 1434-6028 .- 1434-6036. ; 85:11, s. 377-
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Tidskriftsartikel (refereegranskat)abstract
- Unwanted stiction in micro-and nanomechanical (NEMS/MEMS) systems due to dispersion (van der Waals, or Casimir) forces is a significant hurdle in the fabrication of systems with moving parts on these length scales. Introducing a suitably dielectric liquid in the interspace between bodies has previously been demonstrated to render dispersion forces repulsive, or even to switch sign as a function of separation. Making use of recently available permittivity data calculated by us we show that such a remarkable nonmonotonic Casimir force, changing from attractive to repulsive as separation increases, can in fact be observed in systems where constituent materials are in standard NEMS/MEMS use requiring no special or exotic materials. No such nonmonotonic behaviour has been measured to date. We calculate the force between a silica sphere and a flat surface of either zinc oxide or hafnia, two materials which are among the most prominent for practical microelectrical and microoptical devices. Our results explicate the need for highly accurate permittivity functions of the materials involved for frequencies from optical to far-infrared frequencies. A careful analysis of the Casimir interaction is presented, and we show how the change in the sign of the interaction can be understood as a result of multiple crossings of the dielectric functions of the three media involved in a given set-up.
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| 27. |
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| 28. |
- Carlsson, K. Steen, et al.
(författare)
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Costs of diabetes complications : hospital based care and production loss for 392,200 people with type 2 diabetes and matched controls in Sweden
- 2020
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Ingår i: Diabetologia. - : Springer. - 0012-186X .- 1432-0428. ; 63:Suppl. 1, s. S121-S121
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: The prevalence of diabetes has increased rapidly over the last decades worldwide. The risk of complications and medical consequences is well known and identified as key driver of costs. Less evidence on the impact of individual diabetic complications on the societal burden is available. The objective was to analyse costs of hospital-based health care and work absence related to individual macrovascular and microvascular complications of type 2 diabetes in Sweden in 2016.Materials and methods: The study used data from a Swedish retrospective observational database cross-linking 20 years of individual-level data (1997-2016) from national population-based health, social insurance and socio-economic registers for 392,200 people with type 2 diabetes and matched controls (5:1). Diabetes status and presence of 19 types of complications were derived from years 1997-2016 while the costs of hospital-based care and of production loss due to diabetes complications were estimated for 2016. Regression analysis was used for comparison to controls, to attribute production loss to individual complications, and to account for joint presence of complications.Results: Complications are prevalent and patterns complex in type 2 diabetes (Fig. 1). Use of hospital care for complications was higher compared to controls: 86,104 vs 24,608 outpatient visits per 100,000 persons and 9,894 vs 2,546 inpatient admissions per 100,000 persons (p<0.001) in 2016. 26% vs 12% had ≥1 hospital contact. The corresponding total costs of hospital-based care fo rcomplications were EUR 91,875 vs EUR 23,222 per 100 persons (p<0.001) and 75% were directly attributed to diabetes (EUR 689/person). Regression analyses distributed the costs of days absent from work across diabetes complications, basic type 2 diabetes effect and unattributed causes: diabetes complications amounted to EUR 2,165/person in 2016. Key drivers of costs of production loss were macrovascular complications angina pectoris, heart failure and stroke, and microvascular complications eye disease including retinopathy, kidney disease and neuropathy. Early mortality in working ages cost additional EUR 579/person and medications used in risk-factor treatment amounted to EUR 418/person.Conclusion: The economic burden of complications in type 2 diabetes is substantial. Costs of productivity loss in this study were found to be greater than those of hospital-based care highlighting the need for considering treatment consequences in a societal perspective in research and policy.
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| 29. |
- Ceberg, Sofie, et al.
(författare)
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Tumor-tracking radiotherapy of moving targets; verification using 3D polymer gel, 2D ion-chamber array and biplanar diode array
- 2010
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 250:1, s. 235-239
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to carry out a dosimetric verification of a dynamic multileaf collimator (DMLC)-based tumor-tracking delivery during respiratory-like motion. The advantage of tumor-tracking radiation delivery is the ability to allow a tighter margin around the target by continuously following and adapting the dose delivery to its motion. However, there are geometric and dosimetric uncertainties associated with beam delivery system constraints and output variations, and several investigations have to be accomplished before a clinical integration of this tracking technique. Two types of delivery were investigated in this study I) a single beam perpendicular to a target with a one dimensional motion parallel to the MLC moving direction, and II) an intensity modulated arc delivery (RapidArc®) with a target motion diagonal to the MLC moving direction. The feasibility study (I) was made using an 2D ionisation chamber array and a true 3D polymer gel. The arc delivery (II) was verified using polymer gel and a biplanar diode array. Good agreement in absorbed dose was found between delivery to a static target and to a moving target with DMLC tracking using all three detector systems. However, due to the limited spatial resolution of the 2D array a detailed comparison was not possible. The RapidArc® plan delivery was successfully verified using the biplanar diode array and true 3D polymer gel, and both detector systems could verify that the DMLC-based tumor-tracking delivery system has a very good ability to account for respiratory target motion.
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| 30. |
- Chang, Jui-Che, et al.
(författare)
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HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
- 2023
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).
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| 31. |
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| 32. |
- Ding, Haoming, et al.
(författare)
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Synthesis of MAX phases Nb2CuC and Ti2(Al0.1Cu0.9)N by A-site replacement reaction in molten salts
- 2019
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Ingår i: Materials Research Letters. - : Taylor & Francis. - 2166-3831. ; 7:12, s. 510-516
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Tidskriftsartikel (refereegranskat)abstract
- New MAX phases Ti2(AlxCu1−x)N and Nb2CuC were synthesized by A-site replacement by reacting Ti2AlN and Nb2AlC, respectively, with CuCl2 or CuI molten salt. X-ray diffraction, scanning electron microscopy, and atomically resolved scanning transmission electron microscopy showed complete A-site replacement in Nb2AlC, which lead to the formation of Nb2CuC. However, the replacement of Al in Ti2AlN phase was only close to complete at Ti2(Al0.1Cu0.9)N. Density-functional theory calculations corroborated the structural stability of Nb2CuC and Ti2CuN phases. Moreover, the calculated cleavage energy in these Cu-containing MAX phases are weaker than in their Al-containing counterparts.The preparation of MAX phases Nb2CuC and Ti2(Al0.1Cu0.9)N were realized by A-site replacement in Ti2AlN and Nb2AlN, respectively.
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| 33. |
- Dobrovolskiy, Alexander, et al.
(författare)
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Effects of Polytypism on Optical Properties and Band Structure ofIndividual Ga(N)P Nanowires from Correlative Spatially Resolved Structural and Optical Studies
- 2015
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 15:6, s. 4052-4058
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Tidskriftsartikel (refereegranskat)abstract
- III-V semiconductor nanowires (NWs) have gained significant interest as building blocks in novel nanoscale devices. The one-dimensional (1D) nanostructure architecture allows one to extend band structure engineering beyond quantum confinement effects by utilizing formation of different crystal phases that are thermodynamically unfavorable in bulk materials. It is therefore of crucial importance to understand the influence of variations in the NWs crystal structure on their fundamental physical properties. In this work we investigate effects of structural polytypism on the optical properties of gallium phosphide and GaP/GaNP core/shell NW structures by a correlative investigation on the structural and optical properties of individual NWs. The former is monitored by transmission electron microscopy, whereas the latter is studied via cathodoluminescence (CL) mapping. It is found that structural defects, such as rotational twins in zinc blende (ZB) GaNP, have detrimental effects on light emission intensity at low temperatures by promoting nonradiative recombination processes. On the other hand, formation of the wurtzite (WZ) phase does not notably affect the CL intensity neither in GaP nor in the GaNP alloy. This suggests that zone folding in WZ GaP does not enhance its radiative efficiency, consistent with theoretical predictions. We also show that the change in the lattice structure have negligible effects on the bandgap energies of the GaNP alloys, at least within the range of the investigated nitrogen compositions of <2%. Both WZ and ZB GaNP are found to have a significantly higher efficiency of radiative recombination as compared with that in parental GaP, promising for potential applications of GaNP NWs as efficient nanoscale light emitters within the desirable amber-red spectral range.
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| 34. |
- Dorri, Samira, 1988-, et al.
(författare)
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Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition
- 2024
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584.
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Tidskriftsartikel (refereegranskat)abstract
- Single-crystal CrB2/TiB2 diboride superlattices with well-defined layers are promising candidates for neutron optics. However, excess B in sputter-deposited TiBy using a single TiB2 target deteriorates the structural quality of CrBx/TiBy (0001) superlattices. We study the influence of co-sputtering of TiB2 + Ti on the stoichiometry and crystalline quality of 300-nm-thick TiBy single layers and CrBx/TiBy (0001) superlattices on Al2O3(0001) substrates grown by DC magnetron sputter epitaxy at growth-temperatures TS ranging from 600 to 900 °C. By controlling the relative applied powers to the TiB2 and Ti magnetrons, y could be reduced from 3.3 to 0.9. TiB2.3 grown at 750 °C exhibited epitaxial domains about 10x larger than non-co-sputtered films. Close-to-stoichiometry CrB1.7/TiB2.3 superlattices with modulation periods Λ = 6 nm grown at 750 °C showed the highest single crystal quality and best layer definition. TiB2.3 layers display rough top interfaces indicating kinetically limited growth while CrB1.7 forms flat and abrupt top interfaces indicating epitaxial growth with high adatom mobility.
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| 35. |
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| 36. |
- Eklund, Per, et al.
(författare)
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Structural, electrical, and mechanical properties of nc-TiC/a-SiC nanocomposite thin films
- 2005
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 23:6, s. 2486-2495
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Tidskriftsartikel (refereegranskat)abstract
- We have synthesized Ti–Si–C nanocomposite thin films by dc magnetron sputtering from a Ti3SiC2 compound target in an Ar discharge on Si(100), Al2O3(0001), and Al substrates at temperatures from room temperature to 300 °C. Electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy showed that the films consisted of nanocrystalline (nc-) TiC and amorphous (a-) SiC, with the possible presence of a small amount of noncarbidic C. The growth mode was columnar, yielding a nodular film-surface morphology. Mechanically, the films exhibited a remarkable ductile behavior. Their nanoindentation hardness and E-modulus values were 20 and 290 GPa, respectively. The electrical resistivity was 330 µ cm for optimal Ar pressure (4 mTorr) and substrate temperature (300 °C). The resulting nc-TiC/a-SiC films performed well as electrical contact material. These films' electrical-contact resistance against Ag was remarkably low, 6 µ at a contact force of 800 N compared to 3.2 µ for Ag against Ag. The chemical stability of the nc-TiC/a-SiC films was excellent, as shown by a Battelle flowing mixed corrosive-gas test, with no N, Cl, or S contaminants entering the bulk of the films.
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| 37. |
- El Ghazaly, Ahmed, et al.
(författare)
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Enhanced supercapacitive performance of Mo1.33C MXene based asymmetric supercapacitors in lithium chloride electrolyte
- 2021
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Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 41, s. 203-208
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional (2D) Mo1.33C MXene renders great potential for energy storage applications and is mainly studied in the sulfuric acid (H2SO4) electrolyte. However, H2SO4 limits the electrode potential to 0.9 V for symmetric devices and 1.3 V for asymmetric devices. Herein, we explore the electrochemical behavior of Mo1.33C MXene in LiCl electrolyte. In comparison to H2SO4, LiCl electrolyte is a neutral salt with high solubility at room temperature and low hazardousness. The analysis shows a volumetric capacitance of 815 Fcm(-3) at a scan rate of 2 mVs(-1) with a large operating potential window of -1.2 to +0.3V (vs. Ag/AgCl). This is further exploited to construct MXene-based asymmetric supercapacitors Mo1.33C//MnxOn, and the electrochemical performance is evaluated in 5M LiCl electrolyte. Owing to the wide voltage widow of the Mo1.33C//MnxOn devices (2V) and high packing density of the electrodes, we have achieved a volumetric energy density of 58 mWh/cm(3), a maximum power density of 31 Wcm(-3) and retained 92% of the initial capacitance after 10,000 charge/discharge cycles at 10 A g(-1). One of the main value propositions of this work, aside from the high energy density, is the outstanding columbic efficiency (100%), which ensures excellent cyclic stability and is highly desirable for practical applications.
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| 38. |
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| 39. |
- Filippov, Stanislav, et al.
(författare)
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Origin of strong photoluminescence polarization in GaNP nanowires
- 2014
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 14:9, s. 5264-5269
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Tidskriftsartikel (refereegranskat)abstract
- The III-V semiconductor nanowires (NWs) have a great potential for applications in a variety of future electronic and photonic devices with enhanced functionality. In this work, we employ polarization resolved micro-photoluminescence (µ-PL) spectroscopy to study polarization properties of light emissions from individual GaNP and GaP/GaNP core/shell nanowires (NWs) with average diameters ranging between 100 and 350 nm. We show that the near-band-edge emission, which originates from the GaNP regions of the NWs, is strongly polarized (up to 60 % at 150 K) in the direction perpendicular to the NW axis. The polarization anisotropy can be retained up to room temperature. This polarization behavior, which is unusual for zinc blende NWs, is attributed to local strain in the vicinity of the N-related centers participating in the radiative recombination and to preferential alignment of their principal axis along the growth direction. Our findings therefore show that defect engineering via alloying with nitrogen provides an additional degree of freedom to tailor the polarization anisotropy of III-V nanowires, advantageous for their applications as nanoscale emitters of polarized light.
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| 40. |
- Filippov, Stanislav, et al.
(författare)
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Strongly polarized quantum-dot-like light emitters embedded in GaAs/GaNAs core/shell nanowires
- 2016
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Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 8:35, s. 15939-15947
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Tidskriftsartikel (refereegranskat)abstract
- Recent developments in fabrication techniques and extensive investigations of the physical properties of III-V semiconductor nanowires (NWs), such as GaAs NWs, have demonstrated their potential for a multitude of advanced electronic and photonics applications. Alloying of GaAs with nitrogen can further enhance the performance and extend the device functionality via intentional defects and heterostructure engineering in GaNAs and GaAs/GaNAs coaxial NWs. In this work, it is shown that incorporation of nitrogen in GaAs NWs leads to formation of three-dimensional confining potentials caused by short-range fluctuations in the nitrogen composition, which are superimposed on long-range alloy disorder. The resulting localized states exhibit a quantum-dot like electronic structure, forming optically active states in the GaNAs shell. By directly correlating the structural and optical properties of individual NWs, it is also shown that formation of the localized states is efficient in pure zinc-blende wires and is further facilitated by structural polymorphism. The light emission from these localized states is found to be spectrally narrow (similar to 50-130 mu eV) and is highly polarized (up to 100%) with the preferable polarization direction orthogonal to the NW axis, suggesting a preferential orientation of the localization potential. These properties of self-assembled nano-emitters embedded in the GaNAs-based nanowire structures may be attractive for potential optoelectronic applications.
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| 41. |
- Folkenant, Matilda, et al.
(författare)
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Structure and properties of Cr–C/Ag films deposited by magnetron sputtering
- 2015
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 281, s. 184-192
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Tidskriftsartikel (refereegranskat)abstract
- Cr–C/Ag thin films with 0–14 at.% Ag have been deposited by magnetron sputtering from elemental targets. The samples were analyzed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to study their structure and chemical bonding. A complex nanocomposite structure consisting of three phases; nanocrystalline Ag, amorphous CrCx and amorphous carbon is reported. The carbon content in the amorphous carbide phase was determined to be 32–33 at.% C, independent of Ag content. Furthermore, SEM and XPS results showed higher amounts of Ag on the surface compared to the bulk. The hardness and Young's modulus were reduced from 12 to 8 GPa and from 270 to 170 GPa, respectively, with increasing Ag content. The contact resistance was found to decrease with Ag addition, with the most Ag rich sample approaching the values of an Ag reference sample. Initial tribological tests gave friction coefficients in the range of 0.3 to 0.5, with no clear trends. Annealing tests show that the material is stable after annealing at 500 °C for 1 h, but not after annealing at 800 °C for 1 h. In combination, these results suggest that sputtered Cr–C/Ag films could be potentially applicable for electric contact applications.
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| 42. |
- Forsberg, Urban, 1971-, et al.
(författare)
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Growth of high quality AlN Epitaxial Films by Hot-Wall Chemical Vapour Deposition
- 1998
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Ingår i: Proceedings of the International Conference on Silicon Carbide, III-Nitrides and Related Materials, 1997. ; , s. 1133-1136
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Konferensbidrag (refereegranskat)abstract
- Epitaxial films of high quality AlN have been grown on SiC substrates at 1200 °C and 1450 °C, using a hot-wall CVD reactor. The thickness of the epitaxial layers were measured using room temperature infrared reflectance. To verify the crystal quality, X-ray diffraction (XRD) rocking curves of the ALN 0002 peak were measured. A 250 Å thick film grown at 1450°C had a full width half maximum (FWHM) of 42 arcsec, whereas a 1000 Å thick film grown at 1200 °C had a FWHM of 100 arcsec. A TEM image of the sample grown at the lower temperature showed thickness of around 950 Å, thereby verifying the infrared reflectance measurements. We conclude that the higher temperature the better the crystal quality we obtain.
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| 43. |
- Forsén, Rikard, et al.
(författare)
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Nanostructuring and coherency strain in multicomponent hard coatings
- 2014
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Ingår i: APL Materials. - : American Institute of Physics (AIP). - 2166-532X. ; 2:11, s. 116104-
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Tidskriftsartikel (refereegranskat)abstract
- Lattice resolved and quantitative compositional characterizations of the microstructure in TiCrAlN wear resistant coatings emerging at elevated temperatures are performed to address the spinodal decomposition into nanometer-sized coherent cubic TiCr- and Al-rich domains. The domains coarsen during annealing and at 1100 ºC, the Al-rich domains include a metastable cubic Al(Cr)N phase containing 9 at.% Cr and a stable hexagonal AlN phase containing less than 1 at.% Cr. The cubic and the hexagonal phases form strained semi-coherent interfaces with each other.
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| 44. |
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| 45. |
- Ghafoor, Naureen, et al.
(författare)
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Effects of ion-assisted growth on the layer definition in Cr/Sc multilayers
- 2008
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Ingår i: Thin Solid Films. - : Institutionen för fysik, kemi och biologi. - 0040-6090 .- 1879-2731. ; 516:6, s. 982-990
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Tidskriftsartikel (refereegranskat)abstract
- Nano-structural evolution of layer morphology and interfacial roughness in Cr/Sc metal multilayers grown with ion assistance during magnetron sputter deposition has been investigated by high resolution transmission electron microscopy and hard X-ray reflectivity. Calculations based on a binary collision model predict an ion-assisted growth window for optimized Cr/Sc multilayer interface sharpness, within the ion energy range of 21 eV to 37 eV and an ion flux of 10 ions per deposited atom. Multilayers with nominal modulation periods in the range of 1.6 nm to 10.2 nm, grown with these conditions, exhibit a well-defined layer structure with an improved flattening and abruptness of the interfaces. It is shown that multilayers with a modulation period smaller than 3.4 nm have clear benefit from the reduced intermixing obtained by utilizing a two-stage ion energy modulation for each individual layer. The amorphization of Sc and Cr layers, below certain thicknesses, is found to be independent of the low energy ion-assistance. It is also shown that the Cr/Sc multilayers, containing periods less than 2 nm are ‘self healing’ i.e. they re-gain abrupt interfaces and flat layers after morphological disturbances during ion assisted growth. In comparison, multilayers grown without ion-assistance exhibited severe roughness and layer distortions.
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| 46. |
- Ghafoor, Naureen, et al.
(författare)
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Interface engineered ultra-short period Cr/Ti multilayers as high reflectance mirrors and polarizers for soft X-rays of lambda=2.74 nm wavelength
- 2006
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 45:1, s. 137-143
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Tidskriftsartikel (refereegranskat)abstract
- Cr-Ti multilayers with ultrashort periods of 1.39-2.04 nm have been grown for the first time as highly reflective, soft-x-ray multilayer, near-normal incidence mirrors for transition radiation and Cherenkov radiation x-ray sources based on the Ti-2p absorption edge at E = 452eV (lambda = 2.74 nm). Hard, as well as soft, x-ay reflectivity and transmission electron microscopy were used to characterize the nanostructure of the mirrors. To achieve minimal accumulated roughness, improved interface flatness, and to avoid intermixing at the interfaces, each individual layer was engineered by use of a two-stage ion assistance process during magnetron sputter deposition: The first 0.3 nm of each Ti and Cr layer was grown without ion assistance, and the remaining 0.39-0.72 nm of the layers were grown with high ion-neutral flux ratios Phi˙(PhiTi = 3.3, PhiCr = 2.2) and a low energy Eion (ETi = 23.7 and ECr = 21.2), ion assistance. A maximum soft-x-ray reflectivity of R = 2.1% at near-normal incidence (~78.8°) was achieved for a multilayer mirror containing 100 bilayers with a modulation period of 1.379 nm and a layer thickness ratio of Gamma = 0.5. For a polarizing multilayer mirror with 150 bilayers designed for operation at the Brewster angle, 45°, an extinction ratio, Rs/Rp, of 266 was achieved with an absolute reflectivity of R = 4.3%.
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| 47. |
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| 48. |
- Halim, Joseph, 1985-, et al.
(författare)
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Synthesis of Two-Dimensional Nb1.33C (MXene) with Randomly Distributed Vacancies by Etching of the Quaternary Solid Solution (Nb2/3Sc1/3)2AlC MAX Phase
- 2018
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 1:6, s. 2455-2460
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Tidskriftsartikel (refereegranskat)abstract
- Introducing point defects in two-dimensional (2D) materials can alter or enhance their properties. Here, we demonstrate how etching a laminated (Nb2/3Sc1/3)2AlC MAX phase (solid solution) of both the Sc and Al atoms results in a 2D Nb1.33C material (MXene) with a large number of vacancies and vacancy clusters. This method is applicable to any quaternary, or higher, MAX phase, wherein one of the transition metals is more reactive than the other and could be of vital importance in applications such as catalysis and energy storage. We also report, for the first time, on the existence of solid solution (Nb2/3Sc1/3)3AlC2 and (Nb2/3Sc1/3)4AlC3 phases.
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| 49. |
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| 50. |
- Hellgren, Niklas, et al.
(författare)
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Synthesis and characterization of TiBx (1.2=x=2.8) thin films grown by DC magnetron co-sputtering from TiB2 and Ti targets
- 2022
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Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 433
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Tidskriftsartikel (refereegranskat)abstract
- Titanium boride, TiBx, thin films were grown by direct current magnetron co-sputtering from a compound TiB2 target and a Ti target at an Ar pressure of 2.2 mTorr (0.3 Pa) and substrate temperature of 450 ?degrees C. While keeping the power of the TiB2 target constant at 250 W, and by varying the power on the Ti target, P-Ti, between 0 and 100 W, the B/Ti ratio in the film could be continuously and controllably varied from 1.2 to 2.8, with close-tostoichiometric diboride films achieved for P-Ti = 50 W. This was done without altering the deposition pressure, which is otherwise the main modulator for the composition of magnetron sputtered TiBx diboride thin films. The film structure and properties of the as-deposited films were compared to those after vacuum-annealing for 2 h at 1100 ?degrees C. As-deposited films consisted of small (?50 nm) randomly oriented TiB2 crystallites, interspersed in an amorphous, sometimes porous tissue phase. Upon annealing, some of the tissue phase crystallized, but the diboride average grain size did not change noticeably. The near-stoichiometric film had the lowest resistivity, 122 mu omega cm, after annealing. Although this film had growth-induced porosity, an interconnected network of elongated crystallites provides a path for conduction. All films exhibited high hardness, in the 25-30 GPa range, where the highest value of similar to 32 GPa was obtained for the most Ti-rich film after annealing. This film had the highest density and was nano-crystalline, where dislocation propagation is interrupted by the off-stoichiometric grain boundaries.
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