| 1. |
|
|
| 2. |
- Daniau, A. -L, et al.
(författare)
-
predictability of biomass burning in response to climate changes
- 2012
-
Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 26, s. GB4007-
-
Tidskriftsartikel (refereegranskat)abstract
- Climate is an important control on biomass burning, but the sensitivity of fire to changes in temperature and moisture balance has not been quantified. We analyze sedimentary charcoal records to show that the changes in fire regime over the past 21,000 yrs are predictable from changes in regional climates. Analyses of paleo-fire data show that fire increases monotonically with changes in temperature and peaks at intermediate moisture levels, and that temperature is quantitatively the most important driver of changes in biomass burning over the past 21,000 yrs. Given that a similar relationship between climate drivers and fire emerges from analyses of the interannual variability in biomass burning shown by remote-sensing observations of month-by-month burnt area between 1996 and 2008, our results signal a serious cause for concern in the face of continuing global warming.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Lorenzzi, J., et al.
(författare)
-
Incorporation of group III, IV and V elements in 3C–SiC(1 1 1) layers grown by the vapour–liquid–solid mechanism
- 2010
-
Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 312:23, s. 3443-3450
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a comparative investigation of the incorporation of group III, IV and V impurities in 3C–SiC heteroepitaxial layers grown by the vapour–liquid–solid (VLS) mechanism on on-axis α-SiC substrates. To this end, various Si-based melts have been used with addition of Al, Ga, Ge and Sn species. Homoepitaxial α-SiC layers grown using Al-based melts were used for comparison purposed for Al incorporation. Nitrogen incorporation depth profile systematically displays an overshoot at the substrate/epilayer interface for all the layers. Ga and Al incorporations follow the same distribution shape as N whereas this is not the case for the isoelectronic impurities Ge and Sn. This suggests some interaction between Ga/Al and N coming from the high bonding energy between the group III and V elements, which does not exist with Ge and Sn. This is why both incorporate as a cluster. A model of incorporation is proposed taking into account metal-N and metal-C bonding energies together with the solid solubility of the corresponding nitrides.
|
|
| 6. |
- Marinova, Maya, et al.
(författare)
-
Structural and Optical Investigation of VLS Grown (111) 3C-SiC Layers on 6H-SiC Substrates in Sn-Based Melts
- 2011
-
Ingår i: Silicon Carbide and Related Materials 2010. ; , s. 165-168
-
Konferensbidrag (refereegranskat)abstract
- The current communication focuses on the investigation of 3C-SiC layers grown by the Vapour-Liquid-Solid mechanism on on-axis Si-face 6H-SiC substrates in SiSn melts with different compositions and at different growth temperatures. The layers are studied by Transmission Electron Microscopy and Low Temperature Photoluminescence. It was found that for melts with Sn concentration higher than 60 at% large Sn-related precipitates are formed. The depth distribution of the Sn precipitates strongly depends not only on the melt composition but also on the growth temperature. Their formation strongly influences the stacking fault density and the dopant incorporation in the layers. Lower Sn concentrations combined with higher growth temperatures should result in 3C-SiC layer with enhanced structural quality.
|
|
| 7. |
- Robert, T., et al.
(författare)
-
6H-type zigzag faults in low-doped 4H-SiC epitaxial layers.
- 2010
-
Ingår i: Mat. Sci. Forum, Vols. 645-648. - 0878492798 - 9780878492794 ; , s. 347-350
-
Konferensbidrag (refereegranskat)abstract
- A new type of 6H zigzag faults has been identified from high resolution transmission electron microscopy (HRTEM) measurements performed on low-doped 4H-SiC homoepitaxial layer grown on off-axis substrates in a hot-wall CVD reactor. They are made of half unit cells of 6H with corresponding low temperature photoluminescence (LTPL) response ranging from about 3 eV to 2.5 eV at liquid helium temperature.
|
|
| 8. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Effect of initial substrate conditions on growth of cubic silicon carbide
- 2011
-
Ingår i: Journal of Crystal Growth. - : Elsevier Science B.V., Amsterdam.. - 0022-0248 .- 1873-5002. ; 324:1, s. 7-14
-
Tidskriftsartikel (refereegranskat)abstract
- In order to analyze the epitaxial growth of cubic silicon carbide by sublimation epitaxy on different substrates, four different 6H-SiC substrate preparations were used: (i) as-received, (ii) re-polished, (iii) annealed and covered by silicon layer and (iv) with (1 1 1) 3C-SiC buffer layer. Almost 100% coverage and low twin density was achieved when grown on the buffer layer. The XRD and TEM characterizations show better material quality when the layer is grown directly on 6H-SiC substrates. Background doping evaluated by LTPL is in the range of 10(16) cm(-3) for N and 10(16) cm(-3) for Al in all grown layers.
|
|
| 9. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Polytype transformation and structural characteristics of 3C-SiC on 6H-SiC substrates
- 2014
-
Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 395, s. 109-115
-
Tidskriftsartikel (refereegranskat)abstract
- The 3C-SiC (111) was grown on on-axis 6H-SiC substrates in a temperature interval ranging from 1675oC where 3C-SiC nucleated, to 1825oC where coverage of the substrate by 3C-SiC was nearly 100%. The 6H- to 3C-SiC transformation was not abrupt and two different transitions could be observed. The first one occurs before or during 3C-SiC nucleation and consists of 6H-, 3C-, 15R-SiC and other unresolved stacking sequences. The second one appears due to 6H-SiC and 3C-SiC competition during the growth and results in non flat needle-like interface. A proposed model elucidates connection between four-fold twins nucleating at the 6H-/3C-SiC interface and the formation of depressions at the surface of the 3C-SiC layer.
|
|
| 10. |
- Vasiliauskas, Remigijus, et al.
(författare)
-
Sublimation Growth and Structural Characterization of 3C-SiC on Hexagonal and Cubic SiC Seeds
- 2010
-
Ingår i: Materials Science Forum, Vols. 645-648. - : Transtec Publications; 1999. ; , s. 175-178
-
Konferensbidrag (refereegranskat)abstract
- Epitaxial growth of cubic silicon carbide on 6H-SiC substrates, and 6H-SiC substrates with (111) 3C-SiC buffer layer, deposited by vapour liquid solid mechanism, was compared. The morphological details of the grown layers were studied by optical microscopy and their microstructure by transmission electron microscopy. The influence of the substrate on the nucleation of 3C-SiC, the initial homoepitaxial 6H-SiC nucleation before 3C-SiC as well as the formation of defects, are discussed.
|
|
