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- Duane Loh, N., et al.
(författare)
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Profiling structured beams using injected aerosols
- 2012
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Ingår i: Proceedings of SPIE. - : SPIE. - 9780819492210 ; , s. 850403-
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Konferensbidrag (refereegranskat)abstract
- Profiling structured beams produced by X-ray free-electron lasers (FELs) is crucial to both maximizing signal intensity for weakly scattering targets and interpreting their scattering patterns. Earlier ablative imprint studies describe how to infer the X-ray beam profile from the damage that an attenuated beam inflicts on a substrate. However, the beams in-situ profile is not directly accessible with imprint studies because the damage profile could be different from the actual beam profile. On the other hand, although a Shack-Hartmann sensor is capable of in-situ profiling, its lenses may be quickly damaged at the intense focus of hard X-ray FEL beams. We describe a new approach that probes the in-situ morphology of the intense FEL focus. By studying the translations in diffraction patterns from an ensemble of randomly injected sub-micron latex spheres, we were able to determine the non-Gaussian nature of the intense FEL beam at the Linac Coherent Light Source (SLAC National Laboratory) near the FEL focus. We discuss an experimental application of such a beam-profiling technique, and the limitations we need to overcome before it can be widely applied.
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| 4. |
- Welch, C. C., et al.
(författare)
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Formation of nanoscale structures by inductively coupled plasma etching
- 2012
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Ingår i: International Conference Micro- and Nano-Electronics 2012. - : SPIE - International Society for Optical Engineering. - 9780819494870 ; , s. 870002-
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Konferensbidrag (refereegranskat)abstract
- This paper will review the top down technique of ICP etching for the formation of nanometer scale structures. The increased difficulties of nanoscale etching will be described. However it will be shown and discussed that inductively coupled plasma (ICP) technology is well able to cope with the higher end of the nanoscale: features from 100nm down to about 40nm are relatively easy with current ICP technology. It is the ability of ICP to operate at low pressure yet with high plasma density and low (controllable) DC bias that helps greatly compared to simple reactive ion etching (RIE) and, though continual feature size reduction is increasingly challenging, improvements to ICP technology as well as improvements in masking are enabling sub-10nm features to be reached. Nanoscale ICP etching results will be illustrated in a range of materials and technologies. Techniques to facilitate etching (such as the use of cryogenic temperatures) and techniques to improve the mask performance will be described and illustrated.
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| 5. |
- Zerbi, F. M., et al.
(författare)
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HIRES : The High Resolution Spectrograph for E-ELT
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 9780819496157
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Konferensbidrag (refereegranskat)abstract
- The current instrumentation plan for the E-ELT foresees a High Resolution Spectrograph conventionally indicated as HIRES. Shaped on the study of extra-solar planet atmospheres, Pop-III stars and fundamental physical constants, HIRES is intended to embed observing modes at high-resolution (up to R=150000) and large spectral range (from the blue limit to the K band) useful for a large suite of science cases that can exclusively be tackled by the E-ELT. We present in this paper the solution for HIRES envisaged by the "HIRES initiative", the international collaboration established in 2013 to pursue a HIRES on E-ELT.
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| 7. |
- Wang, G., et al.
(författare)
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Integration of selective epitaxial growth of SiGe/Ge layers in 14nm node FinFETs
- 2016
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Ingår i: ECS Transactions. - : Electrochemical Society Inc.. - 1938-5862 .- 1938-6737. - 9781607685395 ; , s. 273-279
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Konferensbidrag (refereegranskat)abstract
- In this study, the process integration of SiGe selective epitaxy on source/drain and SiGe/Ge bilayers selectively epitaxy on replacement Si channel regions for 14 nm node FinFETs has been presented. The epi-quality, layer profile and strain amount of the selectively grown SiGe and Ge layers were also investigated by means of various characterization tools. A series of prebaking experiments were performed for different temperatures in order to in-situ clean the Si fins prior to the SiGe S/D epitaxy. It was also found that a SiGe layer with graded Ge content was deposited as the strain relaxed buffer (SRB) layer in the channel trench prior to the Ge layer filling in the small trenches to make the void defect free.
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| 8. |
- Björk, Robert G., 1974, et al.
(författare)
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Climate-related soil changes in tundra ecosystems at Latnjajaure, northern Sweden – an ITEX-IPY project
- 2010
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Ingår i: International Polar Year Oslo Science Conference.
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Konferensbidrag (refereegranskat)abstract
- During the 90'ies, the International Tundra Experiment (ITEX) was established as a leading project in arctic and alpine ecology, and has become a model for many later network establishments. The present study capitalizes on the early efforts of ITEX and aims at assessing ecosystem changes in the alpine areas of northern Sweden above timberline, i.e. the tundra, in relation to global change. By using the "old" ITEX plots established during the early years of the program we have measured ecosystem respiration (ER), the Normalized Difference Vegetation Index, and nitrogen (N) mineralization over the growing season. In addition, have soil samples been taken to quantify changes in the carbon (C) and N pool, including 13C and 15N. After 12 to 15 years of open top chamber (OTC) treatment no statistical effect was found on the soil temperature (10 cm soil depth), although the was an overall increase in all OTC by +0.2°C. However, the soil moisture decreased significantly by 3-14%, depending on plant community, in the OTCs compared to ambient conditions. Preliminary, there was a 20-37% non-significant higher mean ER in the OTC compared to the ambient plots over the growing season. Furthermore, the OTC treatment did not affect the growing season mineralization of inorganic N, or total C and N content of the soil. The stable isotope data showed both enrichment and depletion as a consequence of the OTC treatment, but no general pattern was discerned. Thus, this non-significant higher ER is most likely of plant origin than soil, as the plant standing biomass has increased in the OTCs. This study does not support the current consensus that tundra soils will alter their C and N dynamics in response to climate change.
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| 9. |
- Björk, Robert G., 1974, et al.
(författare)
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Long-term warming effects on carbon and nitrogen dynamics in tundra soils
- 2012
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Ingår i: 20th Anniversary ITEX Workshop, El Paso, USA, 17–21 January 2012.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During IPY 2008 we used the ITEX experiment in Latnjajaure (northern Sweden), established during the early years of the program, to investigate long-term warming effects on ecosystem respiration (ER), carbon (C) and nitrogen (N) pool (including d13C and d15N), soil organic C (SOC) chemical composition, and N mineralization among plant communities. After 12 to 15 years of open top chamber (OTC) treatment no statistical effect was found on the soil temperature (10 cm soil depth), although the was an overall increase in all OTC by +0.2°C. However, the soil moisture decreased significantly by 3-14%, depending on plant community, in the OTCs compared to ambient conditions. Preliminary, there was a 19-61% non-significant increase in annual growing season ER in the OTC compared to the ambient plots over the growing season. The were distinct differences in the SOM functional composition among plant communities with c 10% more O-alkyls stored in tussock tundra than in dry meadow. The OTCs did not consistently alter the SOM composition among the vegetation types but clearly showed a trend for reduced aliphatic and O-alkyl C in the OTCs suggesting increased decomposition (or reduced inputs) of these compounds. Thus, the non-significantly higher ER may in some communities be of plant origin linked to greater plant biomass in the OTCs, and in other (e.g. tussock tundra) from increased decomposition rates. In conclusion, this study showed that 12-15 years of OTC treatment had a modest effects impact C and N dynamics in tundra soils specific to distinct plant communities.
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