| 1. |
- Wahab, Qamar Ul, et al.
(författare)
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4H-and 6H-SiC MOSFETs fabricated on sloped sidewalls formed by molten KOH etching
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 1215-1218
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Konferensbidrag (refereegranskat)abstract
- Vertical 4H- and 6H-SiC MOSFETs have been fabricated on sloped sidewalls formed by molten KOH etching, which is expected to be free from the damage onto a channel region caused by a dry etching process. The slope angle could be controlled by adjusting etching temperature, and the anisotropy of inversion channel mobility was investigated. A higher inversion channel mobility and a lower threshold voltage were observed with increasing slope angle of channel region toward (1 (1) over bar 00) or (11 (2) over bar0). The highest mobility was 32 cm(2)/Vs for 6H-SiC, which is relatively high as an inversion channel mobility of UMOSFETs compared to previous works. The dependence of device performance on the slope angle and crystal orientation is discussed.
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| 2. |
- Kamiyama, S., et al.
(författare)
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Extremely high quantum efficiency of donor-acceptor-pair emission in N-and-B-doped 6H-SiC
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 99:9
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Tidskriftsartikel (refereegranskat)abstract
- High-efficiency visible light emission in N-and-B-doped 6H-SiC epilayers was observed in photoluminescence measurements at room temperature. The orange-yellow light emission due to the recombination of donor-acceptor pairs (DAPs) has a broad spectrum with a peak wavelength of 576 nm and a full width at half maximum of 110 nm at 250 K. The high B concentration of more than 1018 cm-3 improves the emission efficiency of the DAP recombination at a high temperature. Compared with the photoluminescence spectrum of GaN at 10 K, a high quantum efficiency of 95% was estimated for the highly B-doped sample. From time-resolved photoluminescence measurements, a DAP recombination time of 5.0 ms was obtained, which is in good agreement with the calculated value by the rate equation with the assumption of a 95% internal quantum efficiency. This is quite promising as a light-emitting medium by optical pumping, as well as monolithic light sources combined with nitride-based light-emitting diodes grown on the DA-doped SiC epilayer. © 2006 American Institute of Physics.
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| 3. |
- Yahiro, H., et al.
(författare)
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Copper-phthalocyanine encapsulated into zeolite-Y with high Si/Al : An EPR study
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 415:1-3, s. 126-130
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Tidskriftsartikel (refereegranskat)abstract
- Copper (II) phthalocyanine (CuPc) molecules encapsulated into zeolite-Y with Si/Al ratios of 2.7 and 410 were prepared by an in situ synthesis and characterized by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. Resolved Cu-hyperfine and N-superhyperfine structures were observed in the EPR spectrum of CuPc encapsulated into zeolite-Y with a high Si/Al ratio. UV-Vis and EPR studies as well as theoretical calculations suggest that the encapsulated CuPc molecule was distorted in zeolite-Y with keeping of the square-planar symmetry around the center copper (II) ion. © 2005 Elsevier B.V. All rights reserved.
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| 4. |
- Zetterling, Carl-Mikael, et al.
(författare)
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SiC MISFETs with MBE-grown AlN gate dielectric
- 2000
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 338-342, s. 1315-1318
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Tidskriftsartikel (refereegranskat)abstract
- Metal-Insulator-Semiconductor Field Effect Transistors (MISFETs) with ion implanted source and drain junctions have been made in 6H silicon carbide (SiC). Aluminum nitride (AlN) was used as the insulating gate dielectric, and was grown using molecular beam epitaxy (MBE). Gate controlled transistor operation was shown with an inversion layer mobility of 10-20 cm2/Vs. However, due to relaxation of the AlN film, the gate leakage was excessive, which precluded a thorough investigation of the transistor characteristics. This paper describes the manufacturing process and current voltage characteristics, and an improved process sequence is also proposed.
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| 6. |
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| 7. |
- Pälike, Heiko, et al.
(författare)
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A Cenozoic record of the equatorial Pacific carbonate compensation depth
- 2012
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 488:7413, s. 609-614
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.
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