| 1. |
- Lindehammer, Sabina, et al.
(author)
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Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk
- 2008
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In: Acta Diabetologica. - : Springer Science and Business Media LLC. - 0940-5429 .- 1432-5233. ; 45:4, s. 231-5
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Journal article (peer-reviewed)abstract
- The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.
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| 2. |
- Arvidsson, Igor, 1976-
(author)
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Theoretical Investigations of Boron Related Materials Using DFT
- 2007
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Doctoral thesis (other academic/artistic)abstract
- In the history of Chemistry, materials chemists have developed their ideas mainly by doing experiments in laboratories. The underlying motivation for this laboratory work has generally been pure curiosity or the ambition to find a solution to a specific problem. Minor changes in the composition or structure of a material can cause major changes in its properties. The development of powerful computers has now opened up the possibility to calculate properties of new materials using quantum mechanical methods.The Chemistry of different boron-related materials has been evaluated in this thesis by Density Functional Theory (DFT). Cubic boron nitride (c-BN) is a most interesting material for the microelectronics and tool industry. During thin film deposition of c-BN, several problems arise which most often result in unwanted BN isomorphs. Chemical processes at the (110) and (111) surface of c-BN have been investigated in order to shed light upon some of these complex processes. Typically adsorption energies and surface reconstruction were found to differ significantly between the two surfaces. Other materials investigated are layered transition-metal diborides (MeB2). Incorporation of transition-metal atoms into elemental boron in its most fundamental structure, ά-boron, has also been investigated. The calculations on MeB2 focused on the stability of the planar compared to the puckered structure of MeB2. Stability was investigated by calculating Density of States (DOS) and bond populations. Deviations in the cell parameters from their ideal values were also considered. A separate project concerned reactivity of the TiB2(001) surface. Molecular and dissociated adsorption energies and adsorption geometries were calculated for H2, H2O and O2. It was concluded that the titanium surface was more reactive than the boron surface and that the adsorption energies were comparable to or stronger than other well known surface-active compounds like TiO2.
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| 3. |
- Eskhult, Jonas, 1977-
(author)
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Electrochemical Deposition of Nanostructured Metal/Metal-Oxide Coatings
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Electrochemical deposition finds applications in the electronics- and protective coating industries. The technique is a versatile tool for the synthesis of alloys and thin films. Knowledge of the fundamental aspects of the electrode processes enables the design of nanostructured materials. In this thesis, electrodeposition processes in solutions containing metal ion complexes were studied and new methods for the preparation of metal/metal-oxide coatings were developed and evaluated. Metal/metal oxide coatings were electrodeposited from aqueous solutions containing metal complexes of hydroxycarboxylic acids under reducing conditions. The mass changes of the working electrode were monitored in-situ with the electrochemical quartz crystal microbalance (EQCM) technique and ellipsometry was used to detect the formation of Cu2O. The coatings were further characterized with XRD, XPS, SEM, TEM, and Raman spectroscopy. Electrochemical methods, including reduction of Sb/Sb2O3 in an organic electrolyte, were also used to study the properties of the deposited materials. Nanostructured coatings of Cu/Cu2O were obtained during spontaneous potential or current oscillations in alkaline Cu(II)-citrate solutions. The oscillations were due to local pH variations induced by a subsequent chemical step and comproportionation between Cu and Cu2+. Well-defined layers of Cu and Cu2O could be prepared by a galvanostatic pulsing technique, allowing independently controlled thickness of several hundred nanometers. Coatings, containing Sb and co-deposited, nanograins of Sb2O3, with a thickness of up to 200 nm were prepared from poorly buffered Sb(III)-tartrate solutions. Galvanostatic cycling showed that the latter material could be reversibly charged and discharged in a Li-ion battery for more than 50 cycles with a capacity of 660 mAh/g. The results show that precipitations of metal oxides can occur due to local pH increases during electrochemical deposition from metal complexes with ligands containing hydroxyl groups. The ability to deposit metal oxides using cathodic deposition relies on a sufficiently slow reduction of the oxide.
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| 4. |
- Fallberg, Anna, et al.
(author)
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CVD of Copper(I) Nitride
- 2009
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In: Chemical Vapor Deposition. - Weinheim : WILEY-VCH Verlag GmbH & Co. - 0948-1907 .- 1521-3862. ; 15:10-12, s. 300-305
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Journal article (peer-reviewed)abstract
- Copper(I) nitride (Cu3N) is deposited by CVD using copper(II) hexafluoroacetylacetonate (Cu(hfaC)(2)), ammonia, and water as precursors. The influences of process parameters on growth rate, phase content, chemical composition and morphology are studied. The introduction of water is found to increase film growth rate on the SiO2 substrate. Films are deposited in the temperature range 250-550 degrees C. Single-phase Cu3N is obtained up to 400 degrees C. A phase mixture Of Cu3N and Cu is obtained at 425 degrees C, while a temperature of 550 degrees C and above yields single-phase Cu. X-ray diffraction (XRD) confirms that Cu3N has the cubic, anti-ReO3-type structure; with a cell parameter in the range 3.805-3.816 angstrom. X-ray photoelectron spectroscopy (XPS) verifies the Cu3N stoichiometry. The films are free from impurities (below the detection limit of 1%) at a large excess of ammonia. Scanning electron microscopy (SEM) shows facetted grains, with the faces becoming more well-defined at higher temperatures.
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| 5. |
- Lindahl, Erik, et al.
(author)
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Atomic Layer Deposition of NiO by the Ni(thd)2/H2O Precursor Combination
- 2009
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In: Chemical Vapor Deposition. - : WILEY. - 0948-1907 .- 1521-3862. ; 15:7-9, s. 186-191
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Journal article (peer-reviewed)abstract
- Polycrystalline nickel oxide is deposited on SiO2 substrates by alternating pulses of bis(2,2,6,6-tetramethylheptane-3,5-dionato)nickel(II) (Ni(thd)(2)) and H2O. The deposition process shows atomic layer deposition (ALD) characteristics with respect to the saturation behavior of the two precursors at deposition temperatures up to 275 degrees C. The growth of nickel oxide is shown to be highly dependent on surface hydroxide groups, and a large excess of H2O is required to achieve saturation. Throughout the deposition temperature range the amount of carbon in the film, originating from the metal precursor ligand, is in the range 1-2%. Above 275 degrees C ALD growth behavior is lost in favor of thermal decomposition of the metal precursor. The initial nucleation process is studied by atomic force microscopy (AFM) and reveals nucleation of well-separated grains which coalesce to a continuous film after about 250 ALD cycles.
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| 6. |
- Lindahl, Erik, et al.
(author)
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Chemical Vapour Deposition of Metastable Ni3N
- 2009
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In: EuroCVD17/CVD17. - : The Electrochemical Society. - 9781607680956 ; , s. 365-372
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Conference paper (peer-reviewed)abstract
- Metastable nickel nitride (Ni3N) has been chemically vapour deposited by the use of bis(2,2,6,6-tetramethyl-3,5-heptanedionato)Ni(II) (Ni(thd)2) and ammonia precursors. The growth on both non-etched Si(100) and amorphous SiO2 is polycrystalline at deposition temperatures between 200-290{degree sign}C. However, at the highest temperatures the impurity level of oxygen and carbon originating from the metal precursor ligand, is about 5%. The growth rate dependence of temperature is divided into three different regions with large differences in activation energies, interpreted as different factors controlling the growth. In addition the deposition rate as a function of precursor supply as well as the incubation time for the growth initiation are different at temperatures which are further indications of differences in reaction mechanism. By substitution of NH3 for H2 to the reactant gas the growth mechanism is shown to occur via surface -NHx groups.
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| 7. |
- Lindahl, Erik, 1979-, et al.
(author)
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Epitaxial NiO(100) and NiO(111) films grown by atomic layer deposition
- 2009
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In: Journal of Crystal Growth. - : Elsevier. - 0022-0248 .- 1873-5002. ; 311:16, s. 4082-4088
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Journal article (peer-reviewed)abstract
- Epitaxial NiO (1 1 1) and NiO (1 0 0) films have been grown by atomic layer deposition on both MgO (1 0 0) and alpha-Al2O3 (0 0 1) substrates at temperatures as low as 200 degrees C by using bis(2,2,6,6-tetramethyl-3,5-heptanedionato)Ni(II) and water as precursors. The films grown on the MgO (1 0 0) substrate show the expected cube on cube growth while the NiO (1 1 1) films grow with a twin rotated 180 degrees on the alpha-Al2O3 (0 0 1) substrate surface. The films had columnar microstructures on both substrate types. The single grains were running throughout the whole film thickness and were significantly smaller in the direction parallel to the surface. Thin NiO (1 1 1) films can be grown with high crystal quality with a FWHM of 0.02-0.05 degrees in the rocking curve measurements.
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| 8. |
- Lindahl, Erik, 1979-
(author)
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Thin Film Synthesis of Nickel Containing Compounds
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Most electrical, magnetic or optical devices are today based on several, usually extremely thin layers of different materials. In this thesis chemical synthesis processes have been developed for growth of less stable and metastable layers, and even multilayers, of nickel containing compounds. A chemical vapor deposition (CVD) method for deposition of metastable Ni3N has been developed. The deposition process employs ammonia as nitrogen precursor. An atomic layer deposition (ALD) process for deposition of both polycrystalline and epitaxial NiO and using low oxygen activity, has also been developed. Both deposition processes utilizes bis(2,2,6,6-tetramethyl-3,5-heptanedionato)nickel(II) (Ni(thd)2) as the metal precursor. The Ni3N deposition proceeds via surface reactions. The growth rate is very sensitive to the partial pressure of ammonia, why adsorbed –NHx species are believed to be of importance for the film growth. Similar reactions can be expected between the metal precursor and H2O. For ALD of NiO a large excess of water was needed For the multilayered structures of Ni3N/NiO, growth processes, working at low activities of oxygen and hydrogen, are needed to avoid oxidation or reduction of the underlying layer. Chemical vapor growth methods such as CVD and ALD are often suffering from using high activities of hydrogen or oxygen to deposit metals and oxides. An alternative deposition pathway for metal deposition, without any hydrogen in the vapor, has been demonstrated. The metal has been formed by decomposition of the metastable nitride Ni3N in a post-annealing process. Ni3N decomposes via different mechanisms, depending on environment in the annealing process. The different mechanisms result in different degrees of ordering in the resulting Ni films. From the knowledge gained about the chemical growth of NiO and Ni3N as well as the decomposition of Ni3N, well-defined multilayer structures have been produced in different combinations of NiO, Ni3N and Ni.
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| 9. |
- Lu, Jun, et al.
(author)
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Analytical TEM characterization of the interfacial layer between ALD Hf02 film and silicon substrate
- 2005
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In: Journal of Crystal Growth. ; :273, s. 510-514
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Journal article (peer-reviewed)abstract
- High-resolution transmission electron microscopy and electron energy loss spectrometry were used to characterizethe interfacial layer formed between the silicon substrate and the HfO2 thin film grown by atomic layer deposition (ALD) from HfIU4 and O2. The interfacial layer was amorphous and contained SiO2 mixed with a small amount of elemental Si on the atomic level. The interfacial silicon oxide layer was mainly deposited at the beginning of the ALD process since its thickness was insensitive to the number of applied ALD cycles when increased from 50 to 1000.
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| 10. |
- Mecea, Vasile Mihai, et al.
(author)
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Out-of-plane vibrations of quartz resonators used in quartz crystal microbalance measurements in gas phase
- 2006
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In: Sensors and Actuators A. - : Elsevier BV. - 0924-4247. ; 125:2, s. 143-147
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Journal article (peer-reviewed)abstract
- The article reveals that shear-mode quartz crystal resonators, currently used in quartz crystal microbalance (QCM) measurements, exhibit an out-of-plane vibration without being in contact with a liquid. Laser assisted CVD was used to deposit carbon-nanoparticles on the surface of a quartz resonator. The in-plane, shear vibration of the quartz resonator, produces a mega-gravity acceleration which induces a sedimentation of the carbon-nanoparticles, while the out-of-plane vibration produces a mega-gravity acceleration, normal to the crystal surface, which induces an expelling of the deposited carbon-nanoparticles. The two opposite effects reveal a complex situation on the quartz resonator surface in QCM measurements.
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