| 1. |
- Johansson, H. I P, et al.
(författare)
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Core-level shifts on Be(101̄0)
- 1994
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 49:24, s. 17460-17463
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Tidskriftsartikel (refereegranskat)abstract
- A high-resolution photoemission study of the Be (101̄0) surface, at a sample temperature of 100 K, is reported. Three surface-shifted Be 1s components are revealed having shifts of -700, -500, and -220 meV. These are interpreted as originating from the first, second, and third plus fourth atomic layers while the bulk signal originates from the fifth and deeper layers. The surface layer shift for this more open Be(101̄0) surface is found to be smaller than for the close-packed Be(0001) surface. Reasons for this unusual behavior are suggested.
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| 2. |
- Johansson, L. I., et al.
(författare)
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Surface core level shift on Be( 112̄0)
- 1994
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 321:3
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Tidskriftsartikel (refereegranskat)abstract
- A photoemission study of the Be(112̄0) surface carried out at a sample temperature of 100 K is reported. A surface shifted Be 1s component, having a shift of - 410 meV, is resolved on this surface. The extracted surface to bulk intensity ratio indicate that this component originates from atoms in the surface layer only. This is opposite to previous observations on both the close-packed Be(0001) surface and the Be(101̄0) surface where sub-surface shifted Be 1s levels were unambiguously identified. Among these three surfaces a surface layer atom is expected to have the lowest coordination on the (112̄0) surface but the surface layer shift is found to be smallest on this surface. Compared to findings on other metals this is unusual and reasons contributing to this behaviour are suggested and discussed.
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| 3. |
- Johansson, L. I., et al.
(författare)
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Three surface-shifted core levels on Be(0001)
- 1993
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Ingår i: Physical Review Letters. - 0031-9007. ; 71:15, s. 2453-2456
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Tidskriftsartikel (refereegranskat)abstract
- The results of a high resolution photoemission study of the Be(0001) surface carried out at temperatures between 100 and 450 K are reported. At 100 K, three distinctly shifted Be 1s levels, exhibiting shifts of -825, -570, and -265 meV, are revealed and interpreted to originate from the three outermost atomic layers. Identification of two subsurface core level shifts and a first layer surface shift of -825 meV is unique among close-packed metal surfaces. Temperature dependent broadening effects observed in the bulk and surface BE 1s peaks are also reported.
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| 4. |
- Aad, G., et al.
(författare)
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- 2013
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Ingår i: Journal of High Energy Physics. - 1029-8479 .- 1126-6708. ; :3
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Barrigón, E., et al.
(författare)
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GaAs Nanowire pn-Junctions Produced by Low-Cost and High-Throughput Aerotaxy
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 1088-1092
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires could significantly boost the functionality and performance of future electronics, light-emitting diodes, and solar cells. However, realizing this potential requires growth methods that enable high-throughput and low-cost production of nanowires with controlled doping. Aerotaxy is an aerosol-based method with extremely high growth rate that does not require a growth substrate, allowing mass-production of high-quality nanowires at a low cost. So far, pn-junctions, a crucial element of solar cells and light-emitting diodes, have not been realized by Aerotaxy growth. Here we report a further development of the Aerotaxy method and demonstrate the growth of GaAs nanowire pn-junctions. Our Aerotaxy system uses an aerosol generator for producing the catalytic seed particles, together with a growth reactor with multiple consecutive chambers for growth of material with different dopants. We show that the produced nanowire pn-junctions have excellent diode characteristics with a rectification ratio of >105, an ideality factor around 2, and very promising photoresponse. Using electron beam induced current and hyperspectral cathodoluminescence, we determined the location of the pn-junction and show that the grown nanowires have high doping levels, as well as electrical properties and diffusion lengths comparable to nanowires grown using metal organic vapor phase epitaxy. Our findings demonstrate that high-quality GaAs nanowire pn-junctions can be produced using a low-cost technique suitable for mass-production, paving the way for industrial-scale production of nanowire-based solar cells.
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| 6. |
- de Rojas, I., et al.
(författare)
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Common variants in Alzheimer’s disease and risk stratification by polygenic risk scores
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Genetic discoveries of Alzheimer’s disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer’s disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer’s disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer’s disease. © 2021, The Author(s).
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| 7. |
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| 8. |
- Hammar, M., et al.
(författare)
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Morphology and atomic structure of the sputtered and annealed Mo3Si and Cr3Si (110) surfaces
- 1994
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Ingår i: Physical Review B. - 0163-1829. ; 50:23, s. 17639-17642
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy was used to study the sputtered and annealed (110) surfaces of Mo3Si and Cr3Si. Both surfaces show extended and atomically flat terraces, but in the case of Mo3Si there is also a uniform distribution of Mo crystallites. This difference in morphology is discussed in terms of different preferential sputtering effects. In both cases, measured step heights show that the ideally bulk-truncated surfaces are either purely Si or metal terminated. Atomically resolved images suggest that the Mo3Si surface is Si terminated, but although no atomic resolution could be obtained for the Cr3Si surface, there are indications that this surface is instead metal terminated. © 1994 The American Physical Society.
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| 9. |
- Hammar, M., et al.
(författare)
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Surface atomic structure of reconstructed VC0.8(111) studied with scanning tunneling microscopy
- 1992
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Ingår i: Physical Review B. - 0163-1829. ; 45:11, s. 6118-6123
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Tidskriftsartikel (refereegranskat)abstract
- Scanning tunneling microscopy has been performed on the reconstructed polar surface of substoichiometric VC0.80(111). A mixture of (8×1) and (3 × 3) R30°reconstructed areas was found. The (8×1) periodicity could be determined to be the result of a square-lattice surface layer superimposed on the hexagonal substrate. As this square lattice must have its origin in strong and directed in-plane bonds with the relatively large length of about 2.9, it can be deduced to consist of vanadium atoms. Lateral positions of these vanadium surface atoms with respect to the substrate are suggested from the measured surface corrugation. The (3 × 3) R30°structure was found in small triangular areas which can, due to the measured step heights between the two reconstructions, be believed to be carbon terminated. The occurrence of a reconstructed surface with a reduced atomic concentration is in contrast to what is known for TiC(111) and NbC(111), both having stable (1×1) surfaces. A qualitative explanation for this difference is suggested. © 1992 The American Physical Society.
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| 10. |
- Håkansson, K. L., et al.
(författare)
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High-resolution core-level studies of VC0.80 surfaces
- 1993
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Ingår i: Physical Review B. - 0163-1829. ; 47:16, s. 10769-10774
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution core-level-photoemission investigations of the (100), (111)-1×1, and (111)-8×1 surfaces of VC0.80 using synchrotron radiation are reported. Surface-shifted C 1s levels were observed on all three surfaces while surface-shifted V 2p levels could not be identified on any of the surfaces. The surface core-level shifts were extracted using a curve-fitting procedure. For the major surface-shifted component which was identified on all three surfaces, a shift of -0.33(±0.02) eV was determined. For the (111)-8×1 surface a second shifted component having a shift of +0.44(±0.02) eV was identified. © 1993 The American Physical Society.
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