| 1. |
- Abdi, Y., et al.
(författare)
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Light-emitting nano-porous silicon structures fabricated using a plasma hydrogenation technique
- 2005
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Ingår i: Materials Science and Engineering B: Solid-State Materials for Advanced Technology. - : Elsevier BV. - 0921-5107. ; 124-125:SUPPL., s. 483-487
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Tidskriftsartikel (refereegranskat)abstract
- The preparation of porous silicon films by DC-plasma hydrogenation and subsequent annealing of amorphous silicon films on silicon and glass substrates is reported for the first time. The effects of varying plasma power and annealing temperatures have been investigated and characterized by scanning-electron microscopy, transmission-electron microscopy, and photoluminescence. A plasma density of about 5.5 W/m2 and hydrogenation-annealing temperatures of about 400 °C was found to be suitable for the formation of nano-crystalline silicon films with grain diameters of the order of 3-10 nm. The intensity and wavelength of the emitted visible light were found to depend on the hydrogenation and annealing conditions, and patterning of the silicon films using standard lithography allowed the creation of light-emitting patterns.
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| 2. |
- Derakhshandeh, J., et al.
(författare)
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Fabrication of 100 nm gate length MOSFET's using a novel carbon nanotube-based nano-lithography
- 2005
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5107 .- 1873-4944. ; 124, s. 354-358
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Tidskriftsartikel (refereegranskat)abstract
- PECVD-grown carbon nanotubes on (100)silicon substrates have been studied and exploited for electron emission applications. After the growth of vertical CNT's [Y. Abdi, J. Koohsorkhi, J. Derakhshandeh, S. Mohajerzadeh, H. Hosseinzadegan, M.D. Robertson, C. Benet, EMRS Spring Meeting, Strasbourg, France, May 2005] the grown nanotubes are encapsulated by means of an insulating TiO(2) layer, leading to beam-shape emission of electrons from the cathode towards the opposite anode electrode. The electron emission occurs using an anode-cathode voltage of 100 V with ability of direct writing on a photo-resist-coated substrates. Straight lines with widths between 50 and 200 nm have been successfully drawn. This technique has been applied on P-type (100)silicon substrates for the formation of the gate of N-MOSFET devices. The successful realization of MOSFET devices indicates its usefulness for applications in nano-electronic devices. This device has inversion Cox exceeding 0.7 mu F/cm(2), drive current equal to 3 10 mu A/mu m.
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| 3. |
- Al-kharusi, Enass Said., et al.
(författare)
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Large-Scale Retrieval of Coloured Dissolved Organic Matter in Northern Lakes Using Sentinel-2 Data
- 2020
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Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 12:1, s. 157-157
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Tidskriftsartikel (refereegranskat)abstract
- Owing to the significant societal value of inland water resources, there is a need for cost-effective monitoring of water quality on large scales. We tested the suitability of the recently launched Sentinel-2A to monitor a key water quality parameter, coloured dissolved organic matter (CDOM), in various types of lakes in northern Sweden. Values of a(420)CDOM (CDOM absorption at 420 nm wavelength) were obtained by analyzing water samples from 46 lakes in five districts across Sweden within an area of approximately 800 km2. We evaluated the relationships between a(420)CDOM and band ratios derived from Sentinel-2A Level-1C and Level-2A products. The band ratios B2/B3 (460 nm/560 nm) and B3/B5 (560 nm/705 nm) showed poor relationships with a(420)CDOM in Level-1C and 2A data both before and after the removal of outliers. However, there was a slightly stronger power relationship between the atmospherically-corrected B3/B4 ratio and a(420)CDOM (R2 = 0.28, n = 46), and this relationship was further improved (R2 = 0.65, n = 41) by removing observations affected by light haze and cirrus clouds. This study covered a wide range of lakes in different landscape settings and demonstrates the broad applicability of a(420)CDOM retrieval algorithms based on the B3/B4 ratio derived from Sentinel-2A. View Full-Text
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| 4. |
- Ardo, Shane, et al.
(författare)
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Pathways to electrochemical solar-hydrogen technologies
- 2018
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry. - 1754-5692 .- 1754-5706. ; 11:10, s. 2768-2783
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Forskningsöversikt (refereegranskat)abstract
- Solar-powered electrochemical production of hydrogen through water electrolysis is an active and important research endeavor. However, technologies and roadmaps for implementation of this process do not exist. In this perspective paper, we describe potential pathways for solar-hydrogen technologies into the marketplace in the form of photoelectrochemical or photovoltaic-driven electrolysis devices and systems. We detail technical approaches for device and system architectures, economic drivers, societal perceptions, political impacts, technological challenges, and research opportunities. Implementation scenarios are broken down into short-term and long-term markets, and a specific technology roadmap is defined. In the short term, the only plausible economical option will be photovoltaic-driven electrolysis systems for niche applications. In the long term, electrochemical solar-hydrogen technologies could be deployed more broadly in energy markets but will require advances in the technology, significant cost reductions, and/ or policy changes. Ultimately, a transition to a society that significantly relies on solar-hydrogen technologies will benefit from continued creativity and influence from the scientific community.
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| 5. |
- Georganos, Stefanos, et al.
(författare)
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Examining the NDVI-rainfall relationship in the semi-arid Sahel using geographically weighted regression
- 2017
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Ingår i: Journal of Arid Environments. - : Elsevier BV. - 0140-1963. ; , s. 64-74
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Tidskriftsartikel (refereegranskat)abstract
- The Sahel of Africa is an eco-sensitive zone with complex relations emerging between vegetation productivity and rainfall. These relationships are spatially non-stationary, non-linear, scale dependant and often fail to be successfully modelled by conventional regression models. In response, we apply a local modelling technique, Geographically Weighted Regression (GWR), which allows for relationships to vary in space. We applied the GWR using climatic data (Normalized Vegetation Difference Index and rainfall) on an annual basis during the growing seasons (June–September) for 2002–2012. The operating scale of the Sahelian NDVI–rainfall relationship was found to stabilize around 160 km. With the selection of an appropriate scale, the spatial pattern of the NDVI-rainfall relationship was significantly better explained by the GWR than the traditional Ordinary Least Squares (OLS) regression. GWR performed better in terms of predictive power, accuracy and reduced residual autocorrelation. Moreover, GWR formed spatial clusters with local regression coefficients significantly higher or lower than those that the global OLS model resulted in, highlighting local variations. Areas near wetlands and irrigated lands displayed weak correlations while humid areas such as the Sudanian region at southern Sahel produced higher and more significant correlations. Finally, the spatial relationship of rainfall and NDVI displayed temporal variations as there were significant differences in the spatial trends throughout the study period.
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