| 1. |
- Buyanova, Irina A, et al.
(författare)
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Unusual effects of hydrogen on electronic and lattice properties of GaNP alloys
- 2006
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 376, s. 568-570
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen incorporation is shown to cause passivation of various N-related localized states and partial neutralization of N-induced changes in the electronic structure of the GaNxP1-x alloys with x < 0.008. According to the performed X-ray diffraction measurements, the hydrogenation is also found to cause strong expansion of the GaNP lattice which even changes from a tensile strain in the as-grown GaNP epilayers to a compressive strain in the post-hydrogenated structures with the highest H concentration. By comparing results obtained using two types of hydrogen treatments, i.e. by implantation from a Kaufman source and by using a remote dc H plasma, the observed changes are shown to be inherent to H due to its efficient complexing with N atoms, whereas possible effects of implantation damage are only marginal. (c) 2005 Elsevier B.V. All rights reserved.
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| 2. |
- Flanagan, Sarah E, et al.
(författare)
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Activating germline mutations in STAT3 cause early-onset multi-organ autoimmune disease.
- 2014
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 46:8, s. 812-814
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Tidskriftsartikel (refereegranskat)abstract
- Monogenic causes of autoimmunity provide key insights into the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in five individuals with a spectrum of early-onset autoimmune disease, including type 1 diabetes. These findings emphasize the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in hyper IgE syndrome.
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| 3. |
- Kaasinen, Mirjami, et al.
(författare)
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Matrix Metalloproteinase 8 Expression in a Tumour Predicts a Favourable Prognosis in Pancreatic Ductal Adenocarcinoma
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:6
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic ductal adenocarcinoma (PDAC) is a significant cause of cancer-related death globally, and, despite improvements in diagnostics and treatment, survival remains poor. Matrix metalloproteinases (MMPs) are enzymes involved in stroma remodelling in inflammation and cancer. MMP-8 plays a varied prognostic role in cancers of the gastrointestinal tract. We examined the prognostic value of MMP-8 immunoexpression in tumour tissue and the amount of MMP-8-positive polymorphonuclear cells (PMNs) in PDAC and their association with immune responses using C-reactive protein (CRP) as a marker of systemic inflammation. Tumour samples from 141 PDAC patients undergoing surgery in 2002–2011 at the Department of Surgery, Helsinki University Hospital were stained immunohistochemically, for which we evaluated MMP-8 expression in cancer cells and the amount of MMP-8-positive PMNs. We assessed survival using the Kaplan–Meier analysis while uni-and multivariable analyses relied on the Cox proportional hazards model. A negative MMP-8 stain and elevated CRP level predicted a poor prognosis (hazard ratio [HR] = 6.95; 95% confidence interval (CI) 2.69–17.93; p < 0.001) compared to a positive stain and low CRP level (<10 mg/L). The absence of PMNs together with an elevated CRP level also predicted an unfavourable outcome (HR = 3.17; 95% CI 1.60–6.30; p = 0.001). MMP-8 expression in the tumour served as an independent positive prognostic factor (HR = 0.33; 95% CI 0.16–0.68; p = 0.003). Tumour MMP-8 expression and a low CRP level may predict a favourable outcome in PDAC with similar results for MMP-8-positive PMNs and low CRP levels. Tumoural MMP-8 expression represents an independent positive prognostic factor in PDAC.
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| 4. |
- Palmquist, Jens-Petter, et al.
(författare)
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Magnetron sputtered epitaxial single-phase Ti3SiC2 thin films
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:5, s. 835-837
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Tidskriftsartikel (refereegranskat)abstract
- We report on the synthesis and characterization of epitaxial single-crystalline Ti3SiC2 films (Mn + 1AXn-phase). Two original deposition techniques are described, (i) magnetron sputtering from Ti3SiC2 compound target and (ii) sputtering from individual titanium and silicon targets with co-evaporated C60 as carbon source. Epitaxial Ti3SiC2 films of single-crystal quality were grown at 900 °C with both techniques. Epitaxial TiC(111) deposited in situ on MgO(111) by Ti sputtering using C60 as carbon source was used to nucleate the Ti3SiC2 films. The epitaxial relationship was found to be Ti3SiC2(0001)//TiC(111)//MgO(111) with the in-plane orientation Ti3SiC2[100]//TiC[101]//MgO[101].
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| 5. |
- Radnóczi, G. Z., et al.
(författare)
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Growth of highly curved Al1-xinxN nanocrystals
- 2005
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 202:7
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Tidskriftsartikel (refereegranskat)abstract
- A materials structure is reported that is characterized by high lattice curvature assigned to a compositional gradient. The phenomenon occurs for physical vapour deposition of Al1-xInxN epitaxial thin films with directional fluxes of Al and In at kinetically limited growth conditions. According to our growth model unit cells are incorporated on the growth surfaces of emerging whiskers (nanowires) with a continuously varying lattice parameter depending on their position with respect to Al- and In-rich sides of the whisker. Such curved crystals are effectively quenched solid solutions. We present a description of this generic, self-assembled curved crystal structure and its implications. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 6. |
- Seppänen, Henri, et al.
(författare)
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One kilometer (1 km) electric solar wind sail tether produced automatically
- 2013
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 84:9
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Tidskriftsartikel (refereegranskat)abstract
- We produced a 1 km continuous piece of multifilament electric solar wind sail tether of μm-diameter aluminum wires using a custom made automatic tether factory. The tether comprising 90 704 bonds between 25 and 50 μm diameter wires is reeled onto a metal reel. The total mass of 1 km tether is 10 g. We reached a production rate of 70 m/24 h and a quality level of 1‰ loose bonds and 2‰ rebonded ones. We thus demonstrated that production of long electric solar wind sail tethers is possible and practical.
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| 7. |
- Seppänen, Timo, et al.
(författare)
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248 nm cathodoluminescence in Al1-xInxN (0001) thin films grown on lattice-matched Ti1-yZryN (111) seed layers by low temperature magnetron sputter epitaxy
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:18
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Tidskriftsartikel (refereegranskat)abstract
- Single-crystal Al0.8 In0.2 N (0001) thin films were grown epitaxially onto lattice-matched Ti0.2 Zr0.8 N (111) seed layers on MgO(111) substrates at 300 °C by magnetron sputter epitaxy. Low-energy ion-assisted epitaxial growth conditions were achieved by applying a substrate potential of -15 V. Cross-sectional high-resolution electron microscopy verified the epitaxy and high-resolution x-ray diffraction ω -rocking scans of the Al0.8 In0.2 N 0002 peak (full width at half maximum ∼2400 arc sec) indicated a high structural quality of the films. Cathodoluminescence measurements performed in a scanning electron microscope at 5 K revealed Al0.8 In0.2 N luminescence at 248 nm, or equivalently 5.0 eV, showing that Al0.8 In0.2 N is a promising material for deep-ultraviolet optoelectronic devices. © 2006 American Institute of Physics.
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| 8. |
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| 9. |
- Seppänen, Timo, 1975-
(författare)
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Growth and Characterization of Metastable Wide Band-Gap Al1-xInxN Epilayers
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- InN to 6.2 eV for AlN, which opens possibilities to engineer opto-electronic devices operating from infra-red to deep ultra-violet wavelengths. Al1-xInxN with the alloy composition x~0.2 can also be used as a lattice-matched electron confinement layer for GaN based electronic devices. However, the ternary Al1-xInxN system exhibits a miscibility gap for compositions in the range 0.1<0.9 where a stable alloy cannot be grown under thermodynamic equilibrium conditions, which is why low temperature growth techniques such as magnetron sputtering are of advantage for their syntheses. This thesis describes the growth and structural characterization of epitaxial 2h-Al1-xInxN(0001) [0<1] thin films synthesized by dual DC reactive Magnetron Sputter Epitaxy (MSE) in an ultra-high vacuum (UHV) deposition system. Growth parameters such as deposition temperature, substrate bias, and magnetron power settings were adjusted in order to control the film stoichiometry and crystallinity. The role of in-situ deposited Ti1-yZryN(111) [0£y£1] seed layers on the Al1-xInxN growth was also investigated. It was found that the ZrN(111) seed layers provide a wider stoichiometric composition region for the wide band-gap nitride at elevated temperatures due to its generally lower lattice mismatch as compared to TiN(111). Microstructural characterization of Al1-xInxN deposited at temperatures from room temperature to 900 °C was carried out by X-ray diffraction (XRD) techniques and transmission electron microscopy (TEM). TEM micrographs revealed a dense and columnar microstructure with column widths ranging from 10 to 200 nm depending on growth temperature and seed layer. In addition, a novel generic growth mode giving rise to extremely curved, though stress-free, crystal lattices was observed and investigated. It was found that these, so called, nano-grass structures arise due to specific kinetic and geometrical limitations during growth. Compositional differences are formed over the columns due to self-shadowing effects, which are partly preserved due to the low surface ad-atom mobility. Thus, extremely curved crystalline columns can be formed. XRD investigations showed thatsingle-phase wurtzite epitaxial Al1-xInxN was obtainable throughout the whole composition range for deposition temperatures of up to 600 °C onto ZrN(111) seed layers. At higher temperatures almost pure hexagonal AlN was formed. XRD and selected area electron diffraction also showed that the Al1-xInxN films were grown hetero-epitaxially onto Ti1-yZryN with the epitaxial relationship: Al1-xInxN(0001) // Ti1-yZryN(111) and Al1-xInxN[11-20] // Ti1-yZryN[110]. Based on the results, pseudo-binary phase diagrams for MSE deposition of 2h-Al1-xInxN, at temperatures up to 1000 °C, onto TiN(111) and ZrN(111) coated MgO(111) could be established. A study on the relationship between the Al1-xInxN mole fraction x, in the range 0.07<0.82, and the lattice parameters was carried out for epitaxial Al1-xInxN(0001)/ Ti1-yZryN/MgO(111) films using Rutherford Backscattering Spectrometry (RBS) and XRD. A non-linear relationship was found with a maximum deviation as large as 37 % from the commonly used linear Vegard’s rule. The highest relative deviations were found at low InN mole fractions, while the largest absolute deviation was found at x=0.63. This shows that Vegard’s rule is not directly applicable to determine the compositions in the Al1-xInxN system. Moreover, the post-growth thermal stability of the Al1-xInxN films was investigated by in-situ annealing in an X-ray diffractometer during extensive time periods at temperatures up to 1300 °C. It was found that the thermal stability of the Al1-xInxN films increased with a decreasing In content. Al0.87In0.13N deposited onto ZrN(111) at 300 °C showed to be stable up to 1050 °C, which is about the growth temperature used for GaN in HVPE, thus showing that Al1-xInxN can be used as a template for lattice-matched growth of GaN devices. An optimized growth process for Al0.8In0.2N(0001) onto lattice matched seed layers of Ti0.2Zr0.8N(111) was developed. A mild ion assistance together with a low deposition temperature was found to give the best over-all epi-layer quality. Full-width-at-halfmaximum (FWHM) values of ~40 arc min. was obtained in XRD rocking mode. Furthermore, luminescence at wavelengths as short as 248 nm was observed in these epilayers by cathodoluminescence (CL) measurements performed at 5 K. The corresponding energy of 5.0 eV is the highest reported to date for Al0.8In0.2N. In summary, these results point on the feasibility of metastable Al0.8In0.2N solid solutions as an active luminous material in opto-electronics. It also shows that MSE-grown Al1-xInxN has a high band gap, which make it an excellent choice as a strong charge carrier confinement epi-layer in lattice matched GaN or In1-zGazN hetero-structures.
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| 10. |
- Seppänen, Timo, 1975-
(författare)
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Magnetron sputter epitaxy of 2h-Al1-xInxN thin films
- 2004
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the growth and structural characterization of epitaxial 2h A11-xInxN ranging from pure A1N to InN [01-xInxN films were synthesized by dual DC reactive Magnetron Sputter Epitaxy (MSE) in an ultra-high vacuum (UHV) system. Growth parameters such as deposition temperature and magnetron power settings were adjusted in order to control the film stoichiometry. The role of in-situ deposited TiN(111) and ZrN(111) seed layers on the A11-xInxN growth was also investigated. It was found that ZrN(111) seed layers provide a wider stoichiometric composition region at elevated temperatures due to its low lattice mismatch as compared to TiN(111). Microstructural characterization of A11-xInxN deposited at temperatures from 300 to 900 °C was carried out by X-ray diffraction (XRD) techniques and transmission electron microscopy (TEM). TEM micrographs revealed a dense and columnar microstructure with column widths ranging from 10 to 200 nm depending on growth temperature and seed layer. In addition, a novel generic growth mode giving rise to extremely curved, though stress- free, crystal lattices was observed and investigated. It was found that these, so called, nano-grass structures arise due to specific kinetic and geometrical limitations during growth. Compositional differences are formed over the columns due to self-shadowing effects, which are partly preserved due to the low surface ad-atom mobility. Thus resulting in extremely curved crystalline columns. XRD investigations showed that single-phase wurtzite epitaxial A11-xInxN was obtainable throughout the whole composition range for deposition temperatures of up to 600 °C onto ZrN(111) seed layers. At higher temperatures almost pure hexagonal A1N was formed. XRD and selected area electron diffraction also showed that the A11-xInxN films were grown hetero-epitaxially onto TiN and ZrN with the epitaxial relationship: A11-xInxN(0001)//TiN(ZrN)(111) and A11-xInxN[10-10]//TiN(ZrN)[110]. In the case of A11-xInxN depositions onto TiN(111) seed layers, a phase separation of A11-xInxN was observed when mid-x compositions was targeted at deposition temperatures of 600 °C. This observation was confirmed by TEM results, which revealed a layered structure with epitaxial 2h-A11-xInxN followed by a nano-crystalline structure. Based on the results, pseudo-binary phase diagrams for MSE deposition of 2h-A11-xInxN, at temperatures up to 1000°C, onto TiN(111) and ZrN(111) coated MgO(111) could be established.
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| 11. |
- Seppänen, Timo, et al.
(författare)
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Magnetron sputter epitaxy of wurtzite Al1-x Inx N (0.1
- 2005
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:8, s. 083503-
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Tidskriftsartikel (refereegranskat)abstract
- Ternary wurtzite Al1-x Inx N thin films with compositions throughout the miscibility gap have been grown onto seed layers of TiN and ZrN by magnetron sputter epitaxy (MSE) using dual reactive direct current magnetron sputter deposition under ultra high vacuum conditions. The film compositions were calculated using Vegard's law from lattice parameters determined by x-ray diffraction (XRD). XRD showed that single-phase Al1-x Inx N alloy films in the wurtzite structure with [0.10 TiN,ZrN <110>. At higher substrate temperatures almost pure AlN was formed. The microstructure of the films was also investigated by high-resolution electron microscopy. A columnar growth mode with epitaxial column widths from 10 to 200 nm was observed. Rocking curve full-width-at-half-maximum measurements revealed highly stressed lattices for growth onto TiN at 600°C. Pseudobinary MSE growth phase field diagrams for Al1-x Inx N onto ZrN and TiN were established for substrate temperatures up to 1000°C. Large regimes for single-phase solid solutions were thus identified with In being the diffusing species. © 2005 American Institute of Physics.
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| 12. |
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| 13. |
- Tungasmita, Sukkaneste, et al.
(författare)
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Growth of epitaxial (SiC)(x)(AlN)(1-x) thin films on 6H-SiC by ion-assisted dual magnetron sputter deposition
- 2002
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 389-3, s. 1481-1484
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Tidskriftsartikel (refereegranskat)abstract
- (SiC)(X)(AIN)(1-X) thin films have been grown epitaxially on vicinal 6H-SiC (0001) by low-energy ion assisted dual magnetron sputtering in UHV conditions. AES showed a decreasing Si and C content for an increasing magnetron power ratio, (P-Al/P-SiC). The epitaxial quality of the films was improved as the SiC fraction increased. Films containing less than 5% of Si and C show an evolution of domain width similar to the growth of pure AIN. HRXRD show a decreased c-axis lattice parameter for a film with composition of AINC(X) (0less than or equal toxless than or equal to0.1), indicating carbon substitution in AIN. CL spectra show defect-related peaks of similar to3.87 and similar to4.70 eV, corresponding to O and C impurities respectively as well as on un-identified peak at similar to3.40 eV.
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