| 1. |
- Ali, Sharafat, et al.
(författare)
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Novel transparent Mg-Si-O-N thin films with high hardness and refractive index
- 2016
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 131, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- There is an increasing demand for glass materials with better mechanical and optical properties for display and electronic applications. This paper describes the deposition of novel thin films of Mg-Si-O-N onto float glass substrates. Amorphous thin films in the Mg-Si-O-N system with high nitrogen and magnesium contents were deposited by reactive RF magnetron co-sputtering from Mg and Si targets in Ar/N2/O2 gas mixtures. The thin films studied span an unprecedented range of compositions up to 45 at% Mg and 80 at% N out of cations and anions respectively. Thin films in the Mg-Si-O-N system were found to be homogeneous and transparent in the visible region. Mechanical properties like hardness (H) and reduced elastic modulus (Er) show high values, up to 21 GPa and 166 GPa respectively. The refractive index (1.87-2.00) increases with increasing magnesium and nitrogen contents.
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| 2. |
- Barankova, Hana, et al.
(författare)
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Reactive Deposition of TiN Films by Magnetron with Magnetized Hollow Cathode Enhanced Target
- 2018
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 152, s. 123-127
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Tidskriftsartikel (refereegranskat)abstract
- Magnetized Hollow Cathode Activated Magnetron in which the target is coupled with the hollow cathode magnetized by the magnetic field of the magnetron was tested in the reactive process of TiN deposition. Increased deposition rate compared to the Ti metal deposition rate was confirmed. The depositions as well as optical measurements were performed at several pressures in the reactor. The results of the TiN reactive deposition are presented and discussed, including the TiN deposition in pure nitrogen.
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| 3. |
- Beshkova, M., et al.
(författare)
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Device applications of epitaxial graphene on silicon carbide
- 2016
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 128, s. 186-197
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Forskningsöversikt (refereegranskat)abstract
- Graphene has become an extremely hot topic due to its intriguing material properties allowing for ground-breaking fundamental research and applications. It is one of the fastest developing materials during the last several years. This progress is also driven by the diversity of fabrication methods for graphene of different specific properties, size, quantity and cost. Graphene grown on SiC is of particular interest due to the possibility to avoid transferring of free standing graphene to a desired substrate while having a large area SiC (semi-insulating or conducting) substrate ready for device processing. Here, we present a review of the major current explorations of graphene on SiC in electronic devices, such as field effect transistors (FET), radio frequency (RF) transistors, integrated circuits (IC), and sensors. The successful role of graphene in the metrology sector is also addressed. Typical examples of graphene on SiC implementations are illustrated and the drawbacks and promises are critically analyzed. (C) 2016 Elsevier Ltd. All rights reserved.
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| 4. |
- Elhag, Sami, et al.
(författare)
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Habit-modifying additives and their morphological consequences on photoluminescence and glucose sensing properties of ZnO nanostructures, grown via aqueous chemical synthesis
- 2015
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Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 116, s. 21-26
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Tidskriftsartikel (refereegranskat)abstract
- Generally, the anisotropic shape of inorganic nano-crystal can be influenced by one or more of different parameters i.e. kinetic energy barrier, temperature, time, and the nature of the capping molecules. Here, different surfactants acting as capping molecules were used to assist the aqueous chemical growth of zinc oxide (ZnO) nanostructures on Au coated glass substrates. The morphology, crystal quality and the photoluminescence (PL) properties of the ZnO nanostructures were investigated. The PL properties of the prepared ZnO nanostructures at room temperature showed a dominant UV luminescence peak, while the "green yellow" emissions were essentially suppressed. Moreover, the ZnO nanostructures were investigated for the development of a glucose biosensor. An adsorbed molecule has direct contribution on the glucose oxidase/ZnO/Au sensing properties. We show that the performance of a ZnO-based biosensor can be improved by tailoring the properties of the ZnO biomolecule interface through engineering of the morphology, effective surface area, and adsorption capability.
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| 5. |
- Fondell, Mattis, et al.
(författare)
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Phase control of iron oxides grown in nano-scale structures on FTO and Si(100) : Hematite, maghemite and magnetite
- 2015
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 117, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that iron oxide in the form of hematite, suitable as absorption material in photo-electrochemical cells, can be produced by pulsed chemical vapour deposition. By choosing carbon monoxide or nitrogen as carrier gases in the process the phase and granularity of the grown material can be controlled. The choice of carrier gas affect the decomposition rate of iron pentacarbonyl used as iron precursor. The iron oxide phase is also dependent on the chosen substrate, here fluorine doped tin oxide and crystalline silicon have been used. Regardless of the substrate nitrogen yields hematite, whereas carbon monoxide gives, magnetite on Si and maghemite on fluorine doped tin oxide. A combination of Raman spectroscopy, X-ray diffraction, and hard X-ray photoelectron spectroscopy were used for characterization of the crystalline phase and chemical composition in the films. Scanning electron microscopy were used to visualise the deposited films' nano-structure.
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| 6. |
- Greczynski, Grzegorz, et al.
(författare)
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Peak amplitude of target current determines deposition rate loss during high power pulsed magnetron sputtering
- 2016
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 124
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Tidskriftsartikel (refereegranskat)abstract
- Film growth rates during DCMS and HIPIMS sputtering in Ar are measured for ten technologically relevant elemental target materials: Al, Si, Ti, Cr, Y, Zr, Nb, Hf, Ta, and W, spanning wide range of masses, ionization energies, and sputter yields. Surprisingly, the ratio of power-normalized HIPIMS and DCMS rates a decays exponentially with increasing peak target current density J(T)(max) for all metals. The effect of J(T)(max) on alpha is dramatic: alpha approximate to 1 in the limit of lowest J(T)(max) values tested (0.04 A/cm(2)) and decreases to only 0.12 with J(T)(max) similar to 3 A/cm(2). With the exception of Al and Si, alpha(J(T)(max)) curves overlap indicating that the debated rate loss in HIPIMS is to large extent determined by the peak amplitude of the HIPIMS target current for all tested metals. Back attraction of ionized target species is responsible for such large variation in a. (C) 2015 Elsevier Ltd. All rights reserved.
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| 7. |
- Greczynski, Grzegorz, 1973-, et al.
(författare)
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Strategy for tuning the average charge state of metal ions incident at the growing film during HIPIMS deposition
- 2015
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Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 116, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- Energy and time-dependent mass spectrometry is used to determine the relative number density of singly- and multiply-charged metal-ion fluxes incident at the substrate during high-power pulsed magnetron sputtering (HIPIMS) as a function of the average noble-gas ionization potential. Ti is selected as the sputtering target since the microstructure, phase composition, properties, and stress-state of Ti-based ceramic thin films grown by HIPIMS are known to be strongly dependent on the charge state of Tin+ (n = 1, 2, …) ions incident at the film growth surface. We find that the flux of Tin+ with n > 2 is insignificant; thus, we measure the Ti2+/Ti+ integrated flux ratio JTi2+ =JTi+ at the substrate position as a function of the choice of noble gase Ne, Ar, Kr, Xe, as well as Ne/Ar, Kr/Ar, and Xe/Ar mixtures – supporting the plasma. We demonstrate that by changing noble-gas mixtures, JTi2+ varies by more than two orders of magnitude with only a small change in JTi+ . This allows the ratio JTi2+ =JTi+ to be continuously tuned from less than 0.01 with Xe, which has a low first-ionization potential IP1, to 0.62 with Ne which has a high IP1. The value for Xe, IP1Xe= 12.16 eV, is larger than the first ionization potential of Ti, IP1Ti= 6.85 eV, but less than the second Ti ionization potential, IP2Ti= 13.62 eV. For Ne, however, IP1Ne= 21.63 eV is greater than both IP1Ti and IP2Ti. Therefore, the high-energy tail of the plasma-electron energy distribution can be systematically adjusted, allowing JTi2+/JTi+ to be controllably varied over a very wide range.
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| 8. |
- Hellgren, Niklas, et al.
(författare)
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High-power impulse magnetron sputter deposition of TiBx thin films : Effects of pressure and growth temperature
- 2019
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 169
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Tidskriftsartikel (refereegranskat)abstract
- Titanium boride, TiBx thin films are grown in pure Ar discharges by high-power impulse magnetron sputtering (HiPIMS) from a compound TiB2 target Film compositions are determined by time-of-flight elastic recoil detection analysis and Rutherford backscattering spectrometry as a function of deposition temperature (T-s = 25-900 degrees C) and Ar pressure (p(Ar) = 0.67-2.67 Pa, 5-20 mTorr). For reference, films are also grown by direct current magnetron sputtering (dcMS) under similar conditions. The HiPIMS waveform, average target power P-T, and resulting film compositions are strongly dependent not only on P-Ar, but also on T-s. At high pressures the effect of varying T-s on P-T is minimal, while at lower P-Ar the effect of T-s is more pronounced, due to substrate-temperature-induced gas rarefaction. Films grown by HiPIMS at 0.67 Pa are understoichiometric, with B/Ti = 1.4-1.5, while at 2.67 Pa, B/Ti decreases from 2.4 to 1.4 as T-s increases from 25 to 900 degrees C. dcMS-deposited films are overstoichiometric (B/Ti similar or equal to 3) when grown at low pressures, and near-stoichiometric (B/Ti similar or equal to r 1.9-2.2) for higher P-Ar. All experimental results are explained by differences in the ionization potentials of sputtered Ti and B atoms, together with P-Ar- and T-s-dependent gas-phase scattering.
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| 9. |
- Hsiao, Ching-Lien, et al.
(författare)
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Nucleation and core-shell formation mechanism of self-induced InxAl1−xN core-shell nanorods grown on sapphire substrates by magnetron sputter epitaxy
- 2016
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Ingår i: Vacuum. - : Pergamon Press. - 0042-207X .- 1879-2715. ; 131, s. 39-43
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Tidskriftsartikel (refereegranskat)abstract
- Nucleation of self-induced nanorod and core-shell structure formation by surface-induced phase separation have been studied at the initial growth stage. The growth of well-separated core shell nanorods is only found in a transition temperature region (600 degrees C amp;lt;= T amp;lt;= 800 degrees C) in contrast to the result of thin film growth outside this region (T amp;lt; 600 degrees C or T amp;gt; 800 degrees C). Formation of multiple compositional domains, due to phase separation, after similar to 20 nm InxAl1-xN epilayer growth from sapphire substrate promotes the core-shell nanorod growth, showing a modified Stranski-Krastanov growth mode. The use of VN seed layer makes the initial growth of the nanorods directly at the substrate interface, revealing a Volmer-Weber growth mode. Different compositional domains are found on VN template surface to support that the phase separation takes place at the initial nucleation process and forms by a self-patterning effect. The nanorods were grown from In-rich domains and initiated the formation of core-shell nanorods due to spinodal decomposition of the InxAl1-xN alloy with a composition in the miscibility gap.
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| 10. |
- Karlsson, Linda, et al.
(författare)
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Graphene on graphene formation from PMMA residues during annealing
- 2017
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 137, s. 191-194
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Tidskriftsartikel (refereegranskat)abstract
- PMMA is a common support material for transferring graphene between substrates. However, PMMA residues typically remain on the graphene sheet after the transfer process. A high temperature annealing process is commonly applied to reduce the amount of PMMA residues. It is also known that high temperature annealing of PMMA causes the PMMA to graphitize, which has been used as a method to synthesize graphene on metal substrates. In this letter we show the development of additional graphene layers during high temperature annealing, which occurs on a single, clean, graphene sheet. The additional graphene is nucleated from the decomposition products of PMMA residues. (C) 2017 Elsevier Ltd. All rights reserved.
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