| 1. |
- Doyle, J P, et al.
(författare)
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Observation of near-surface electrically active defects in n-type 6H-SiC
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83, s. 3649-3651
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Tidskriftsartikel (refereegranskat)abstract
- In n-type 6H-SiC epitaxial layers grown by vapor phase epitaxy, we find that in contrast to the majority of the epitaxial layer, where electrically active defects are observed with a concentration less than 1 X 10(-13) cm(-3), a region near the front surface contains defects with concentrations approaching 10(14) cm(-3). A relationship between the near-surface defects and metallic impurities is suggested by a Ti concentration of 1 X 10(16) cm(-3) in this region. The high concentration of near surface defects is found to significantly reduce the carrier lifetime. (C) 1998 American Institute of Physics. [S0021-8979(98)03007-2].
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| 2. |
- Valenta, J., et al.
(författare)
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Photonic band-gap effects on photoluminescence of silicon nanocrystals embedded in artificial opals
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:8, s. 4471-4474
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Tidskriftsartikel (refereegranskat)abstract
- Si nanocrystals were formed in synthetic opals by Si-ion implantation and their optical properties studied using microphotoluminescence and reflection techniques. The properties of areas with high crystalline quality are compared with those of disordered regions of samples. The photoluminescence spectrum from Si nanocrystals embedded in silica spheres is narrowed by the inhibition of emission at wavelengths corresponding to the opal photonic pseudoband gap (similar to690 nm). Measurements of photoluminescence spectra from individual implanted silica spheres is also demonstrated and the number of emitting Si nanocrystals in single brightly emitting spheres is estimated to be of the order of one thousand.
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| 3. |
- Alme, Tomas Nordheim, et al.
(författare)
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Chronic fatigue syndromes: real illnesses that people can recover from
- 2023
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Ingår i: Scandinavian Journal of Primary Health Care. - : TAYLOR & FRANCIS LTD. - 0281-3432 .- 1502-7724. ; 41:4, s. 372-376
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Tidskriftsartikel (refereegranskat)abstract
- The Oslo Chronic Fatigue Consortium consists of researchers and clinicians who question the current narrative that chronic fatigue syndromes, including post-covid conditions, are incurable diseases. Instead, we propose an alternative view, based on research, which offers more hope to patients. Whilst we regard the symptoms of these conditions as real, we propose that they are more likely to reflect the brains response to a range of biological, psychological, and social factors, rather than a specific disease process. Possible causes include persistent activation of the neurobiological stress response, accompanied by associated changes in immunological, hormonal, cognitive and behavioural domains. We further propose that the symptoms are more likely to persist if they are perceived as threatening, and all activities that are perceived to worsen them are avoided. We also question the idea that the best way to cope with the illness is by prolonged rest, social isolation, and sensory deprivation.Instead, we propose that recovery is often possible if patients are helped to adopt a less threatening understanding of their symptoms and are supported in a gradual return to normal activities. Finally, we call for a much more open and constructive dialogue about these conditions. This dialogue should include a wider range of views, including those of patients who have recovered from them.
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| 4. |
- Badel, Xavier, et al.
(författare)
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Formation of pn junctions in deep silicon pores for X-ray imaging detector applications
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 509:1-3, s. 96-101
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Tidskriftsartikel (refereegranskat)abstract
- The formation of pn junctions in deep silicon pores has been studied for a new concept of X-ray imaging detectors. The sensitive part of the device is an array of CsI(Tl) columns formed by filling a silicon matrix of pores having pn junctions in their walls. Under X-ray illumination, the CsI(TI) scintillator emits photons that are collected by the pn junctions. Relatively high signal collection efficiency is expected. However, the formation of pn junctions inside pore walls represents a challenging step in the detector fabrication. In this work pore matrices were fabricated in n-type silicon by deep reactive ion etching and by photo-electrochemical etching. The pn junctions were formed either by boron diffusion or deposition of boron doped poly-silicon. Various techniques were used to analyze the transverse depth profiles of boron atoms at different pore depths. The study shows successful results for pn-junctions formed both by diffusion and by poly-silicon deposition.
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| 5. |
- Badel, Xavier, et al.
(författare)
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Performance of scintillating waveguides for CCD-based X-ray detectors
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 53:1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- Scintillating films are usually used to improve the sensitivity of CCD-based X-ray imaging detectors. For an optimal spatial resolution and detection efficiency, a tradeoff has to be made on the film thickness. However, these scintillating layers can also be structured to provide a pixellated screen. In this paper, the study of CsI(TI)-filled pore arrays is reported. The pores are first etched in silicon, then oxidized and finally filled with CsI(TI) to form scintillating waveguides. The dependence of the detector sensitivity on pore depth, varied from 40 to 400 mu m here, follows rather well theoretical predictions. Most of the detectors produced in this work have a detective quantum efficiency of the incoming X-ray photons of about 25%. However, one detector shows that higher efficiency can be achieved approaching almost the theoretical limit set by Poisson statistics of the incoming X-rays. Thus, we conclude that it is possible to fabricate scintillating waveguides with almost ideal performance. Imaging capabilities of the detectors are demonstrated.
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| 6. |
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| 7. |
- Dev, Apurba, et al.
(författare)
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Electrokinetic effect for molecular recognition : A label-free approach for real-time biosensing
- 2016
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Ingår i: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 82, s. 55-63
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Tidskriftsartikel (refereegranskat)abstract
- We present a simple and inexpensive method for label-free detection of biomolecules. The method monitors the changes in streaming current in a fused silica capillary as target biomolecules bind to immobilized receptors on the inner surface of the capillary. To validate the concept, we show detection and time response of different protein-ligand and protein-protein systems: biotin-avidin and biotin-streptavidin, barstar-dibarnase and Z domain-immunoglobulin G (IgG). We show that specific binding of these biomolecules can be reliably monitored using a very simple setup. Using sequential injections of various proteins at a diverse concentration range and as well as diluted human serum we further investigate the capacity of the proposed technique to perform specific target detection from a complex sample. We also investigate the time for the signal to reach equilibrium and its dependence on analyte concentration and demonstrate that the current setup can be used to detect biomolecules at a concentration as low as 100 pM without requiring any advanced device fabrication procedures. Finally, an analytical model based on diffusion theory has been presented to explain the dependence of the saturation time on the analyte concentration and capillary dimensions and how reducing length and inner diameter of the capillary is predicted to give faster detection and in practice also lower limit of detection.
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| 8. |
- Duan, M., et al.
(författare)
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Deposition of Scintillating Layers of Bismuth Germanate (BGO) Films for X-ray detector applications
- 1998
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 45:3, s. 525-527
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Tidskriftsartikel (refereegranskat)abstract
- Bi4Ge3O12 films were deposited by pulsed laser ablation on glass and SiO2/Si substrates. The crystal structures of the films depend on the deposition temperature. XRD patterns indicate that the films deposited at substrate temperature less than 400°C are amorphous. The as deposited amorphous films can be crystallized by post rapid thermal annealing (RTA) in the temperature window from 750°C to 800°C for 2 minutes in a oxygen ambient environment. RBS measurements confirm that the films have the same chemical composition as that of the target. The surface morphology of the films were characterized by atomic force microscopy (AFM)
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| 9. |
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| 10. |
- Galeckas, A, et al.
(författare)
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Evaluation of Auger recombination rate in 4H-SiC
- 1998
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Ingår i: Proceedings of the 1997 7th International Conference on Silicon Carbide, III-Nitrides and Related Materials, ICSCIII.. ; , s. 533-536
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Konferensbidrag (refereegranskat)
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