| 1. |
- Blumenau, A.T., et al.
(författare)
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The effect of charge on kink migration at 90° partial dislocations in SiC
- 2005
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 202:5, s. 877-882
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Tidskriftsartikel (refereegranskat)abstract
- SiC bipolar devices show a degradation under forward-biased operation which has been linked with a recombination enhanced motion of one of the two glide dislocations having either Si or C core atoms. We have carried out calculations of the core structures and dynamics of partial dislocations in 3C and 2H-SiC using the density functional based codes DFTB and AIMPRO. After in earlier theoretical work we reported on the structure, energetics and electronic activity of both of the Shockley partials, and on the formation and migration barriers of kinks, in this work we present first results on the effect of charge on the disloction kinks. The calculations give insights into the device degradation mechanism.
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| 2. |
- Goss, J.P., et al.
(författare)
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Planar interstitial aggregates in Si
- 2002
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:48, s. 12843-12853
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Tidskriftsartikel (refereegranskat)abstract
- Self-interstitials in silicon aggregate to form rod-like defects aligned along [110] directions and inhabiting either {111} or {113} crystallographic planes. These systems are known to be electrically and optically active. We present the results of first-principles calculations on the structure and energetics for candidate structures contained within the {113}, {111} and {001} planes and compare the results with experiment.
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| 3. |
- Strosberg, J., et al.
(författare)
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Phase 3 Trial of Lu-177-Dotatate for Midgut Neuroendocrine Tumors
- 2017
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 376:2, s. 125-135
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Patients with advanced midgut neuroendocrine tumors who have had disease progression during first-line somatostatin analogue therapy have limited therapeutic options. This randomized, controlled trial evaluated the efficacy and safety of lutetium-177 (Lu-177)-Dotatate in patients with advanced, progressive, somatostatin-receptor-positive midgut neuroendocrine tumors. METHODS We randomly assigned 229 patients who had well-differentiated, metastatic midgut neuroendocrine tumors to receive either Lu-177-Dotatate (116 patients) at a dose of 7.4 GBq every 8 weeks (four intravenous infusions, plus best supportive care including octreotide long-acting repeatable [LAR] administered intramuscularly at a dose of 30 mg) (Lu-177-Dotatate group) or octreotide LAR alone (113 patients) administered intramuscularly at a dose of 60 mg every 4 weeks (control group). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, safety, and the side-effect profile. The final analysis of overall survival will be conducted in the future as specified in the protocol; a prespecified interim analysis of overall survival was conducted and is reported here. RESULTS At the data-cutoff date for the primary analysis, the estimated rate of progression-free survival at month 20 was 65.2% (95% confidence interval [CI], 50.0 to 76.8) in the Lu-177-Dotatate group and 10.8% (95% CI, 3.5 to 23.0) in the control group. The response rate was 18% in the Lu-177-Dotatate group versus 3% in the control group (P<0.001). In the planned interim analysis of overall survival, 14 deaths occurred in the Lu-177-Dotatate group and 26 in the control group (P = 0.004). Grade 3 or 4 neutropenia, thrombocytopenia, and lymphopenia occurred in 1%, 2%, and 9%, respectively, of patients in the Lu-177-Dotatate group as compared with no patients in the control group, with no evidence of renal toxic effects during the observed time frame. CONCLUSIONS Treatment with Lu-177-Dotatate resulted in markedly longer progression-free survival and a significantly higher response rate than high-dose octreotide LAR among patients with advanced midgut neuroendocrine tumors. Preliminary evidence of an overall survival benefit was seen in an interim analysis; confirmation will be required in the planned final analysis. Clinically significant myelosuppression occurred in less than 10% of patients in the Lu-177-Dotatate group. (Funded by Advanced Accelerator Applications; NETTER-1 ClinicalTrials. gov number, NCT01578239; EudraCT number 2011-005049-11.)
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| 4. |
- Ashwin, M.J., et al.
(författare)
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The bonding of CAs acceptors in InxGa1-xAs grown by chemical beam epitaxy using carbon tetrabromide as the source of carbon
- 1996
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 80:12, s. 6754-6760
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Tidskriftsartikel (refereegranskat)abstract
- InxGa1-xAs layers (0≤x≤0.37) doped with carbon (>1020 cm-3) were grown on semi-insulating GaAs substrates by chemical beam epitaxy using carbon tetrabromide (CBr4) as the dopant source. Hall measurements imply that all of the carbon was present as CAs for values x up to 0.15. The C acceptors were passivated by exposing samples to a radio frequency hydrogen plasma for periods of up to 6 h. The nearest-neighbor bonding configurations of CAs were investigated by studying the nondegenerate antisymmetric hydrogen stretch mode (A-1 symmetry) and the symmetric XH mode (A+1 symmetry) of the H-CAs pairs using IR absorption and Raman scattering, respectively. Observed modes at 2635 and 450 cm-1 had been assigned to passivated Ga4CAs clusters. New modes at 2550 and 430 cm-1 increased in strength with increasing values of x and are assigned to passivated InGa3CAs clusters. These results were compared with ab initio local density functional theory. Modes due to AlInGaCAs clusters were detected in samples containing grown in Al and In. These results demonstrate that for InGaAs, CBr4 is an efficient C doping source since both In-CAs bonds as well as Ga-CAs bonds are formed, whereas there is no evidence for the formation of In-CAs bonds in samples doped with C derived from trimethylgallium or solid sources
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| 5. |
- Beye, M., et al.
(författare)
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Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001)
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:18
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the femtosecond dynamics following optical laser excitation of CO adsorbed on a Ru surface by monitoring changes in the occupied and unoccupied electronic structure using ultrafast soft x-ray absorption and emission. We recently reported [M. Dell'Angela et al. Science 339, 1302 (2013)] a phonon-mediated transition into a weakly adsorbed precursor state occurring on a time scale of >2 ps prior to desorption. Here we focus on processes within the first picosecond after laser excitation and show that the metal-adsorbate coordination is initially increased due to hot-electron-driven vibrational excitations. This process is faster than, but occurs in parallel with, the transition into the precursor state. With resonant x-ray emission spectroscopy, we probe each of these states selectively and determine the respective transient populations depending on optical laser fluence. Ab initio molecular dynamics simulations of CO adsorbed on Ru(0001) were performed at 1500 and 3000 K providing insight into the desorption process.
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| 6. |
- Blumenau, A.T., et al.
(författare)
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Basal plane partial dislocations in silicon carbide
- 2003
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 340, s. 160-164
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Tidskriftsartikel (refereegranskat)abstract
- Under operating conditions (forward bias) bipolar 4H- and 6H-SiC devices are known to degrade rapidly through stacking fault formation and expansion in the basal plane. It has been suggested that a recombination-enhanced dislocation glide (REDG) mechanism allows the bordering Shockley partial dislocations to overcome their barrier to glide motion and thus results in the observed stacking fault growth. In this work, we investigate the structure and properties of the participating Shockley partials by means of density functional-based atomistic calculations. Their glide motion is modelled in a process involving the formation and subsequent migration of kinks. This in combination with an analysis of the electronic structure of the partials allows an identification of those types which will be affected by the REDG mechanism.
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| 7. |
- Blumenau, A.T., et al.
(författare)
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Density functional based modelling of 30° partial dislocations in SiC
- 2004
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Ingår i: Proceedings of the 10th International Conference on Silicon Carbide and Related Materials, ICSCRM 2003. - Stafa-Zuerich : Trans Tech Publications Inc.. - 0878499431 ; , s. 453-456
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Konferensbidrag (refereegranskat)abstract
- Experiment has shown that 4H- and 6H-SiC pin diodes degrade rapidly during forward biased operation. This degradation is accompanied by the formation and expansion of stacking faults in the basal plane. It is believed that the observed rapid stacking fault growth is due to a recombination-enhanced dislocation glide (REDG) mechanism at the bordering partial dislocations. In our work we investigate the structure and properties of basal plane 30° Shockley partials in SiC by means of density functional based calculations. Barriers to their glide motion, and thus the expansion of the accompanying stacking fault is modelled in a process involving the formation and subsequent migration of kinks in the dislocation. In combination with an analysis of the electronic structure of the partials and stacking faults, this allows an identification of those types of partials which will be affected by the REDG mechanism in this model.
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| 8. |
- Blumenau, A. T., et al.
(författare)
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Dislocation related photoluminescence in silicon
- 2001
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 87:18
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Tidskriftsartikel (refereegranskat)abstract
- Dislocation related photoluminescence in Si and SiGe is attributed to stable interstitial clusters bound to 60° dislocations. Density functional based total energy calculations in Si give binding energies between 1.5 and 3.6 eV for I3 and I4 clusters with 90° and 30° partials. They possess donor levels around Ev+0.4 eV which are consistent with deep level transient spectroscopic studies on p-Si. It is further suggested that the clusters would act as the obstacles to the movement of dislocations which may have been observed in recent transmission electron microscopy studies.
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| 9. |
- Blumenau, A.T., et al.
(författare)
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Dislocations in hexagonal and cubic GaN
- 2000
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 12, s. 10223-10233
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Tidskriftsartikel (refereegranskat)abstract
- The structure and electronic activity of several types of dislocations in both hexagonal and cubic GaN are calculated using first-principles methods. Most of the stoichiometric dislocations investigated in hexagonal GaN do not induce deep acceptor states and thus cannot be responsible for the yellow luminescence. However, it is shown that electrically active point defects, in particular gallium vacancies and oxygen-related defect complexes, can be trapped at the stress field of the dislocations and may be responsible for this luminescence. For cubic GaN, we find the ideal stoichiometric 60° dislocation to be electrically active and the glide set to be more stable than the shuffle. The dissociation of the latter is considered
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| 10. |
- Blumenau, A.T., et al.
(författare)
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Optical bands related to dislocations in Si
- 2000
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 12:49, s. 10123-10129
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Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations are used to investigate the interaction of self-interstitial aggregates with the 90° partial dislocation in Si. We find that I4 is bound to the line with an energy of around 3 eV. The defect causes deep levels to appear in the band gap and optical transitions between these levels may account for the luminescent bands relating to plastically deformed Si.
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