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| 2. |
- Kim, Hyeong Seok, et al.
(författare)
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Development, validation, and comparison of a nomogram based on radiologic findings for predicting malignancy in intraductal papillary mucinous neoplasms of the pancreas : An international multicenter study
- 2021
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Ingår i: Journal of hepato-biliary-pancreatic sciences. - : Wiley-Blackwell. - 1868-6974 .- 1868-6982.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although we previously proposed a nomogram to predict malignancy in intraductal papillary mucinous neoplasms (IPMN) and validated it in an external cohort, its application is challenging without data on tumor markers. Moreover, existing nomograms have not been compared. This study aimed to develop a nomogram based on radiologic findings and to compare its performance with previously proposed American and Korean/Japanese nomograms.METHODS: We recruited 3708 patients who underwent surgical resection at 31 tertiary institutions in eight countries, and patients with main pancreatic duct >10 mm were excluded. To construct the nomogram, 2606 patients were randomly allocated 1:1 into training and internal validation sets, and area under the receiver operating characteristics curve (AUC) was calculated using 10-fold cross validation by exhaustive search. This nomogram was then validated and compared to the American and Korean/Japanese nomograms using 1102 patients.RESULTS: Among the 2606 patients, 90 had main-duct type, 900 had branch-duct type, and 1616 had mixed-type IPMN. Pathologic results revealed 1628 low-grade dysplasia, 476 high-grade dysplasia, and 502 invasive carcinoma. Location, cyst size, duct dilatation, and mural nodule were selected to construct the nomogram. AUC of this nomogram was higher than the American nomogram (0.691 vs 0.664, P = .014) and comparable with the Korean/Japanese nomogram (0.659 vs 0.653, P = .255).CONCLUSIONS: A novel nomogram based on radiologic findings of IPMN is competitive for predicting risk of malignancy. This nomogram would be clinically helpful in circumstances where tumor markers are not available. The nomogram is freely available at http://statgen.snu.ac.kr/software/nomogramIPMN.
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| 3. |
- Nik-Zainal, Serena, et al.
(författare)
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Landscape of somatic mutations in 560 breast cancer whole-genome sequences
- 2016
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 534:7605, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- We analysed whole-genome sequences of 560 breast cancers to advance understanding of the driver mutations conferring clonal advantage and the mutational processes generating somatic mutations. We found that 93 protein-coding cancer genes carried probable driver mutations. Some non-coding regions exhibited high mutation frequencies, but most have distinctive structural features probably causing elevated mutation rates and do not contain driver mutations. Mutational signature analysis was extended to genome rearrangements and revealed twelve base substitution and six rearrangement signatures. Three rearrangement signatures, characterized by tandem duplications or deletions, appear associated with defective homologous-recombination-based DNA repair: one with deficient BRCA1 function, another with deficient BRCA1 or BRCA2 function, the cause of the third is unknown. This analysis of all classes of somatic mutation across exons, introns and intergenic regions highlights the repertoire of cancer genes and mutational processes operating, and progresses towards a comprehensive account of the somatic genetic basis of breast cancer.
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| 4. |
- Buono, Benedetto, et al.
(författare)
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Simulations of Open Emitter Breakdown Voltage in SiC BJTs with non Implanted JTE
- 2009
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. ; 615-617, s. 841-844
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Tidskriftsartikel (refereegranskat)abstract
- Ion implantation for selective doping of SiC is problematic due to damage generation during the process and low activation of dopants. In SiC bipolar junction transistor (BJT) the junction termination extension (JTE) can be formed without ion implantation using instead a controlled etching into the epitaxial base. This etched JTE is advantageous because it eliminates ion implantation induced damage and the need for high temperature annealing. However, the dose, which is controlled by the etched base thickness and doping concentration, plays a crucial role. In order to find the optimum parameters, device simulations of different etched base thicknesses have been performed using the software Sentaurus Device. A surface passivation layer consisting of silicon dioxide, considering interface traps and fixed trapped charge, has been included in the analysis by simulations. Moreover a comparison with measured data for fabricated SiC BJTs has been performed.
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| 5. |
- Danielsson, Erik, et al.
(författare)
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A 4H-SiC BJT with an epitaxially regrown extrinsic base layer
- 2005
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 483, s. 905-908
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Tidskriftsartikel (refereegranskat)abstract
- 4H-SiC BJTs were fabricated using epitaxial regrowth instead of ion implantation to form a highly doped extrinsic base layer necessary for a good base ohmic contact. A remaining p(+) regrowth spacer at the edge of the base-emitter junction is proposed to explain a low current gain of 6 for the BJTs. A breakdown voltage of 1000 V was obtained for devices with Al implanted JTE.
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| 6. |
- Domeij, Martin, et al.
(författare)
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Analysis of the base current and saturation voltage in 4H-SiC power BJTs
- 2007
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Ingår i: 2007 European Conference On Power Electronics And Applications. - 9789075815115 ; , s. 2744-2750
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Konferensbidrag (refereegranskat)abstract
- Silicon carbide (SiC) power bipolar junction transistors are interesting competitors to Si IGBTs for 1200 V power electronics applications. Advantages of SiC BJTs are low collector-emitter saturation voltages, little stored charge and high temperature capability. In this work, SiC NPN power BJTs with common emitter current gains of 40 have been fabricated and characterized. Electrical measurements for BJTs with different emitter widths indicate that the current gain is limited by surface recombination. A low value of V-CESAT=0.9 V at J(C)=100 A/cm(2) was obtained for small and large area (3.4 mm(2)) BJTs and correlated with the formation of low-resistive ohmic contacts to the base. Large area BJTs were shown to operate with a current gain of 48 in pulsed mode at a collector current of 12 A corresponding to J(C)=360 A/cm(2).
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| 7. |
- Domeij, Martin, et al.
(författare)
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Current gain dependence on emitter width in 4H-SiC BJTs
- 2006
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Ingår i: Materials Science Forum. - : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. - 9780878494255 ; 527-529, s. 1425-1428
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the fabrication of epitaxial 4H-SiC bipolar junction transistors (BJTs) with a maximum current gain beta = 64 and a breakdown voltage of 1100 V. The high beta value is attributed to high material quality obtained after a continuous epitaxial growth of the base-emitter junction. The current gain of the BJTs increases with increasing emitter width indicating a significant influence of surface recombination. This "emitter-size" effect is in good agreement with device simulations including recombination in interface states at the etched termination of the base-emitter junction.
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| 8. |
- Domeij, Martin, et al.
(författare)
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Current gain of 4H-SiC bipolar transistors including the effect of interface states
- 2005
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Ingår i: Materials Science Forum. - ZURICH-UETIKON : Trans Tech Publications Inc.. - 0255-5476 .- 1662-9752. - 0878499636 ; 483, s. 889-892
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Tidskriftsartikel (refereegranskat)abstract
- The current gain (β) of 4H-SiC BJTs as function of collector current (I-C) has been investigated by DC and pulsed measurements and by device simulations. A measured monotonic increase of β with I-C agrees well with simulations using a constant distribution of interface states at the 4H-SiC/SiO2 interface along the etched side-wall of the base-emitter junction. Simulations using only bulk recombination, on the other hand, are in poor agreement with the measurements. The interface states degrade the simulated current gain by combined effects of localized recombination and trapped charge that influence the surface potential. Additionally, bandgap narrowing has a significant impact by reducing the peak current gain by about 50% in simulations.
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| 9. |
- Domeij, Martin, et al.
(författare)
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Geometrical effects in high current gain 1100-V 4H-SiC BJTs
- 2005
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 26:10, s. 743-745
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the fabrication of epitaxial 4H-SiC bipolar junction transistors (BJTs) with a maximum current gain beta = 64 and a breakdown voltage of 1100 V. The high beta value is attributed to high material quality obtained after a continuous epitaxial growth of the base-emitter junction. The BJTs show a clear emitter-size effect indicating that surface recombination has a significant influence on beta. A minimum distance of 2-3 mu m between the emitter edge and base contact implant was found adequate to avoid a substantial beta reduction.
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| 10. |
- Domeij, Martin, et al.
(författare)
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High current gain silicon carbide bipolar power transistors
- 2006
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Ingår i: Proceedings of the 18th International Symposium on Power Semiconductor Devices and ICs. ; , s. 141-144
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Konferensbidrag (refereegranskat)abstract
- Silicon carbide NPN bipolar junction transistors were fabricated and a current gain exceeding 60 was obtained for a BJT with a breakdown voltage BV(CEO)=1100 V. A reduction of the current gain was observed after contact annealing at 950 degrees C and this was attributed to degradation of the oxide passivation. Device simulations with varying emitter doping resulted in a maximum current gain for an emitter doping around 1(.)10(19) cm(-3). Resistive turn-off measurements were performed and a minimum collector-emitter voltage (V(CE)) rise-time of 40 ns was found. The VCE rise-time showed a clear dependence on the on-state base current thus indicating a significant stored charge.
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