| 1. |
- Buchanan, E. M., et al.
(författare)
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The Psychological Science Accelerator's COVID-19 rapid-response dataset
- 2023
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Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- In response to the COVID-19 pandemic, the Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing, cognitive reappraisals, and autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental study, a general questionnaire examining health prevention behaviors and COVID-19 experience, geographical and cultural context characterization, and demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73,223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore coping, framing, and self-determination across a diverse, global sample obtained at the onset of the COVID-19 pandemic, which can be merged with other time-sampled or geographic data.
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| 2. |
- Buyanova, Irina A, et al.
(författare)
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Unusual effects of hydrogen on electronic and lattice properties of GaNP alloys
- 2006
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 376, s. 568-570
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen incorporation is shown to cause passivation of various N-related localized states and partial neutralization of N-induced changes in the electronic structure of the GaNxP1-x alloys with x < 0.008. According to the performed X-ray diffraction measurements, the hydrogenation is also found to cause strong expansion of the GaNP lattice which even changes from a tensile strain in the as-grown GaNP epilayers to a compressive strain in the post-hydrogenated structures with the highest H concentration. By comparing results obtained using two types of hydrogen treatments, i.e. by implantation from a Kaufman source and by using a remote dc H plasma, the observed changes are shown to be inherent to H due to its efficient complexing with N atoms, whereas possible effects of implantation damage are only marginal. (c) 2005 Elsevier B.V. All rights reserved.
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| 3. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys : a proof for a general property of dilute nitrides
- 2004
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 70:24, s. 245215-245219
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Tidskriftsartikel (refereegranskat)abstract
- Direct experimental evidence for dramatic effects of hydrogen incorporation on the electronic structure and lattice properties of GaNxP1−x alloys is presented. By employing photoluminescence excitation spectroscopy, postgrowth hydrogenation is shown to reopen the band gap of the GaNP alloys and to efficiently reduce the N-induced coupling between the conduction band states. By Raman spectroscopy, these effects are shown to be accompanied by hydrogen-induced breaking of the Ga-P bond in the alloy, evident from disappearance of the corresponding vibrational mode. According to the performed Raman and x-ray diffraction measurements, the hydrogenation is also found to cause a strong expansion of the GaNP lattice, which changes the sign of strain from tensile in the as-grown GaNP epilayers to compressive in the posthydrogenated structures, due to the formation of complexes between N and H.
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| 4. |
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| 5. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Hydrogen-induced improvements in optical quality of GaNAs alloys
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:21, s. 3662-3665
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Tidskriftsartikel (refereegranskat)abstract
- Strong suppression of potential fluctuations in the band edges of GaNAs alloys due to postgrowth hydrogen treatment, which is accompanied by a reopening of the alloy band gap, is revealed from temperature-dependent photoluminescence (PL) and PL excitation measurements. The effect likely indicates preferential trapping of hydrogen near the lattice sites with the highest nitrogen content. A remarkable improvement in the radiative efficiency of the alloys at room temperature is also demonstrated and is ascribed to efficient hydrogen passivation of competing nonradiative centers.
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| 9. |
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| 10. |
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| 11. |
- Dagnelund, Daniel, 1980-, et al.
(författare)
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Activation of defects in GaNP by post-growth hydrogen treatment
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Effect of post-growth hydrogen treatment on defects and their role in carrier recombination in molecular beam epitaxial GaNP alloys is examined by means of photoluminescence and optically detected magnetic resonance. We present direct experimental evidence for effective activation of several different defects in carrier recombination by the hydrogen treatment. Among them, two defect complexes are identified to contain a Ga interstitial (Gai). None of the activated Gai complexes was previously observed in GaNP. Possible mechanisms for the hydrogen-induced defect activation are discussed.
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| 12. |
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| 13. |
- Dagnelund, Daniel, et al.
(författare)
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Effect of postgrowth hydrogen treatment on defects in GaNP
- 2011
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Ingår i: APPLIED PHYSICS LETTERS. - : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 98:14, s. 141920-
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Tidskriftsartikel (refereegranskat)abstract
- Effect of postgrowth hydrogen treatment on defects and their role in carrier recombination in GaNP alloys is examined by photoluminescence (PL) and optically detected magnetic resonance. We present direct experimental evidence for effective activation of several defects by low-energy subthreshold hydrogen treatment (andlt;= 100 eV H ions). Among them, two defect complexes are identified to contain a Ga interstitial. Possible mechanisms for the H-induced defect activation and creation are discussed. Carrier recombination via these defects is shown to efficiently compete with the near band-edge PL, explaining the observed degraded optical quality of the alloys after the H treatment.
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| 14. |
- Dagnelund, Daniel, et al.
(författare)
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Effect of thermal annealing on defects in post-growth hydrogenated GaNP
- 2013
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - : John Wiley & Sons. - 1610-1634 .- 1610-1642. ; 10:4, s. 561-563
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Tidskriftsartikel (refereegranskat)abstract
- Effect of thermal annealing on paramagnetic centers in post-growth hydrogenated GaN0.0081P0.9919 epilayer is examined by means of photoluminescence and optically detected magnetic resonance (ODMR) techniques. In recent studies, several Ga-interstitial (Gai) related centers were found to be activated by the presence of hydrogen in the hydrogenated GaNP alloys. These centers compete with near-band edge radiative recombination. Annealing at 400 ºC in Ar-ambient is found to cause quenching of the Gai-related ODMR signals that were activated by post-growth hydrogenation. We tentatively ascribe this effect to dissociation of the H-Gai complexes and subsequent out-diffusion of H.
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| 15. |
- Dagnelund, Daniel, et al.
(författare)
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Effects of hydrogenation on non-radiative defects in GaNP and GaNAs alloys: An optically detected magnetic resonance study
- 2012
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 111:023501
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Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence and optically detected magnetic resonance techniques are utilized to study defect properties of GaNP and GaNAs alloys subjected to post-growth hydrogenation by low-energy sub-threshold ion beam irradiation. It is found that in GaNP H incorporation leads to activation of new defects, which has a Ga interstitial (Ga-i) atom at its core and may also involve a H atom as a partner. The observed activation critically depends on the presence of N in the alloy, as it does not occur in GaP with a low level of N doping. In sharp contrast, in GaNAs hydrogen is found to efficiently passivate Ga-i-related defects present in the as-grown material. A possible mechanism responsible for the observed difference in the H behavior in GaNP and GaNAs is discussed.
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| 16. |
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| 17. |
- Felici, M, et al.
(författare)
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High Energy Optical Transitions in Ga(PN) : Contribution from Perturbed Valence Band
- 2005
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Ingår i: AIP Conference Proceedings / Volume 772. - : American Institute of Physics (AIP). - 0735402574 ; , s. 265-
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Konferensbidrag (refereegranskat)abstract
- The GaP1–xNx conduction band is investigated experimentally (by excitation photoluminescence) andtheoretically (by pseudopotential supercells) for N concentrations up to x=3.5%and photon energies ranging from the optical absorption edge to3.2 eV. With increasing x: (i) a direct-like absorption edgedevelops smoothly and red-shifts rapidly overtaking energy-pinned cluster states; (ii)a broad absorption plateau appears between the X1c and the1c critical points of GaP; (iii) the 1c absorption edgebroadens and gradually disappears. Empirical pseudopotential calculations for GaP1-xNx randomalloy supercells account well for all the PLE results byconsidering N induced changes in the valence band overlooked sofar. ©2005 American Institute of Physics
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| 18. |
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| 19. |
- Izadifard, Morteza, 1965-, et al.
(författare)
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Role of hydrogen in improving optical quality of GaNAs alloys
- 2003
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Ingår i: 11th Int. Conf. on Narrow Bandgap Semiconductors,2003. - Physica E, Vol 20 : Elsevier. ; , s. 313-316
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Konferensbidrag (refereegranskat)abstract
- Effects of hydrogen irradiation on optical quality of GaNxAs1−x alloys grown by gas source molecular beam epitaxy are studied by photoluminescence (PL) and PL excitation spectroscopies. A strong blue shift of the alloy band gap towards the value of a reference N-free GaAs samples is revealed. Substantial improvements in the optical quality of the structures induced by hydrogen, due to a reduction of band edge potential fluctuations, is also demonstrated. The effect is tentatively attributed to the preferential trapping of hydrogen atoms at the lattice sites with the highest N compositions, which leads to the neutralization of electronic states contributing to the band tail states as well as to the improvement in strain uniformity.
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| 20. |
- Löfdahl, Claes-Göran, et al.
(författare)
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Randomised, placebo controlled trial of effect of a leukotriene receptor antagonist, montelukast, on tapering inhaled corticosteroids in asthmatic patients
- 1999
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Ingår i: BMJ. - 0959-8138. ; 319:7202, s. 87-90
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To determine the ability of montelukast, a leukotriene receptor antagonist, to allow tapering of inhaled corticosteroids in clinically stable asthmatic patients. DESIGN: Double blind, randomised, placebo controlled, parallel group study. After a single blind placebo run in period, during which (at most) two inhaled corticosteroids dose decreases occurred, qualifying, clinically stable patients were allocated randomly to receive montelukast (10 mg tablet) or matching placebo once daily at bedtime for up to 12 weeks. SETTING: 23 academic asthma centres in United States, Canada, and Europe. PARTICIPANTS: 226 clinically stable patients with chronic asthma receiving high doses of inhaled corticosteroids (113 randomised to montelukast and 113 to placebo). INTERVENTIONS: Every 2 weeks, the inhaled corticosteroids dose was tapered, maintained, or increased (rescue) based on a standardised clinical score. MAIN OUTCOME MEASURES: Last tolerated dose of inhaled corticosteroids. RESULTS: Compared with placebo, montelukast allowed significant (P=0. 046) reduction in the inhaled corticosteroid dose (montelukast 47% v placebo 30%; least square mean difference 17.6%, 95% confidence interval 0.3 to 34.8). Fewer patients on montelukast (18 (16%) v 34 (30%) placebo, P=0.01) required discontinuation because of failed rescue. CONCLUSIONS: Montelukast reduces the need for inhaled corticosteroids among patients requiring moderate to high doses of corticosteroid to maintain asthma control.
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| 21. |
- Polimeni, A., et al.
(författare)
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Hydrogen related effects in diluted nitrides
- 2003
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Ingår i: 22nd Int. Conf. on Defects in Semiconductors,2003. - : Elsevier. ; , s. 371-
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Konferensbidrag (refereegranskat)abstract
- Hydrogen irradiation leads to the passivation of the electronic activity of nitrogen in Ga(AsN), thus allowing a fine tuning of the material optical properties. Here, some recent results on the effects that hydrogen irradiation has on the electronic properties of diluted III-N-V alloys are presented. In Ga(AsN), both the increase in the electron effective mass and exciton wave function localization induced by nitrogen are reversed in a fully controllable manner by hydrogen irradiation. In Ga(PN), hydrogen widens the band gap and exposes gradually in the gap nitrogen complex states formerly resonant with the conduction band.
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| 22. |
- Polimeni, A., et al.
(författare)
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Nitrogen passivation induced by atomic hydrogen : The GaP1-yNy case
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 67:20, s. 2013031-2013034
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Tidskriftsartikel (refereegranskat)abstract
- We report on the evolution of the optical properties of GaP1-yNy epilayers upon hydrogen irradiation for an extended nitrogen concentration range (y = 0.05% - 1.3%). For y = 0.6%, photoluminescence measurements show that hydrogen leads to an apparent band gap widening and to an ensuing appearance of N cluster states in the forbidden gap of GaP1-yNy, Hydrogen removal from the samples results in a full recovery of the electronic properties of the as-grown material. For lower N concentration (y = 0.05%), hydrogen causes a spectral weight transfer from electronic levels associated with closer N pairs to those associated with more distant N pairs and single N atoms.
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| 23. |
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| 24. |
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| 25. |
- Puttisong, Yuttapoom, et al.
(författare)
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Room temperature spin filtering effect in GaNAs: Role of hydrogen
- 2011
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 99:15, s. 152109-
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Tidskriftsartikel (refereegranskat)abstract
- Effects of hydrogen on the recently discovered defect-engineered spin filtering in GaNAs are investigated by optical spin orientation and optically detected magnetic resonance. Post-growth hydrogen treatments are shown to lead to nearly complete quenching of the room-temperature spin-filtering effect in both GaNAs epilayers and GaNAs/GaAs multiple quantum wells, accompanied by a reduction in concentrations of Ga(i) interstitial defects. Our finding provides strong evidence for efficient hydrogen passivation of these spin-filtering defects, likely via formation of complexes between Gai defects and hydrogen, as being responsible for the Observed strong suppression of the spin-filtering effect after the hydrogen treatments.
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| 29. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 30. |
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| 31. |
- Bravo, L, et al.
(författare)
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- 2021
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| 32. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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