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| 5. |
- Muench, S., et al.
(författare)
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Time-resolved photoluminescence investigations on HfO2-capped InP nanowires
- 2010
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:10
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Tidskriftsartikel (refereegranskat)abstract
- We have employed time-resolved photoluminescence (PL) spectroscopy to study the impact of HfO2 surface capping by atomic layer deposition (ALD) on the optical properties of InP nanowires (NWs). The deposition of high-kappa dielectrics acting as a gate oxide is of particular interest in view of possible applications of semiconductor NWs in future wrap-gated field effect transistors (FETs). A high number of charged states at the NW-dielectrics interface can strongly degrade the performance of the FET which explains the strong interest in high quality deposition of high-kappa dielectrics. In the present work we show that time-resolved spectroscopy is a valuable and direct tool to monitor the surface quality of HfO2-capped InP NWs. In particular, we have studied the impact of ALD process parameters as well as surface treatment prior to the oxide capping on the NW-dielectrics interface quality. The best results in terms of the surface recombination velocity (S-0 = 9.5 x 10(3) cm s(-1)) were obtained for InP/GaP core/shell NWs in combination with a low temperature (100 degrees C) ALD process. While the present report focuses on the InP material system, our method of addressing the surface treatment for semiconductors with high-kappa dielectrics will also be applicable to nanoelectronic devices based on other III/V material systems such as InAs.
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| 6. |
- Webb, J. L., et al.
(författare)
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Imaging Atomic Scale Dynamics on III-V Nanowire Surfaces during Electrical Operation
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- As semiconductor electronics keep shrinking, functionality depends on individual atomic scale surface and interface features that may change as voltages are applied. In this work we demonstrate a novel device platform that allows scanning tunneling microscopy (STM) imaging with atomic scale resolution across a device simultaneously with full electrical operation. The platform presents a significant step forward as it allows STM to be performed everywhere on the device surface and high temperature processing in reactive gases of the complete device. We demonstrate the new method through proof of principle measurements on both InAs and GaAs nanowire devices with variable biases up to 4 V. On InAs nanowires we observe a surprising removal of atomic defects and smoothing of the surface morphology under applied bias, in contrast to the expected increase in defects and electromigration-related failure. As we use only standard fabrication and scanning instrumentation our concept is widely applicable and opens up the possibility of fundamental investigations of device surface reliability as well as new electronic functionality based on restructuring during operation.
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| 7. |
- Andréasson, Sven, et al.
(författare)
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Psychosocial Treatment for Alcohol Dependence
- 2003
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Ingår i: Treating Alcohol and Drug Abuse : An Evidence Based Review - An Evidence Based Review. - : Wiley. - 352730682X - 9783527306824 - 9783527601462 ; , s. 43-188
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Bokkapitel (refereegranskat)
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| 8. |
- Barker, D., et al.
(författare)
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Individually addressable double quantum dots formed with nanowire polytypes and identified by epitaxial markers
- 2019
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 114:18
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Tidskriftsartikel (refereegranskat)abstract
- Double quantum dots (DQDs) hold great promise as building blocks for quantum technology as they allow for two electronic states to coherently couple. Defining QDs with materials rather than using electrostatic gating allows for QDs with a hard-wall confinement potential and more robust charge and spin states. An unresolved problem is how to individually address these QDs, which is necessary for controlling quantum states. We here report the fabrication of DQD devices defined by the conduction band edge offset at the interface of the wurtzite and zinc blende crystal phases of InAs in nanowires. By using sacrificial epitaxial GaSb markers selectively forming on one crystal phase, we are able to precisely align gate electrodes allowing us to probe and control each QD independently. We hence observe textbooklike charge stability diagrams, a discrete energy spectrum, and electron numbers consistent with theoretical estimates and investigate the tunability of the devices, finding that changing the electron number can be used to tune the tunnel barrier as expected by simple band diagram arguments.
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| 9. |
- Berglund, Mats, et al.
(författare)
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Pharmacotherapy for alcohol dependence
- 2003
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Ingår i: Treatment of Alcohol and Drug Abuse. An Evidence-Based Review. - 9783527306824 - 352730682X ; , s. 4-4
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 13. |
- Burns, Suzanne Perea, et al.
(författare)
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Stroke Recovery During the COVID-19 Pandemic : A Position Paper on Recommendations for Rehabilitation
- 2022
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Ingår i: Archives of Physical Medicine and Rehabilitation. - : Elsevier. - 0003-9993 .- 1532-821X. ; 103:9, s. 1874-1882
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Tidskriftsartikel (refereegranskat)abstract
- Health care delivery shifted and adapted with the COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus 2. Stroke care was negatively affected across the care continuum and may lead to poor community living outcomes in those who survived a stroke during the ongoing pandemic. For instance, delays in seeking care, changes in length of stays, and shifts in discharge patterns were observed during the pandemic. Those seeking care were younger and had more severe neurologic effects from stroke. Increased strain was placed on caregivers and public health efforts, and community-wide lockdowns, albeit necessary to reduce the spread of COVID-19, had detrimental effects on treatment and recommendations to support community living outcomes. The American Congress of Rehabilitation Medicine Stroke Interdisciplinary Special Interest Group Health and Wellness Task Force convened to (1) discuss international experiences in stroke care and rehabilitation and (2) review recently published literature on stroke care and outcomes during the pandemic. Based on the findings in the literature, the task force proposes recommendations and interdisciplinary approaches at the (1) institutional and societal level; (2) health care delivery level; and (3) individual and interpersonal level spanning across the care continuum and into the community.
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| 14. |
- Chabes, Andrei, et al.
(författare)
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Yeast ribonucleotide reductase has a heterodimeric iron-radical-containing subunit
- 2000
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 97:6, s. 2474-2479
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Tidskriftsartikel (refereegranskat)abstract
- Ribonucleotide reductase (RNR) catalyzes the de novo synthesis of deoxyribonucleotides. Eukaryotes have an alpha(2)beta(2) form of RNR consisting of two homodimeric subunits, proteins R1 (alpha(2)) and R2 (beta(2)). The R1 protein is the business end of the enzyme containing the active site and the binding sites for allosteric effectors. The R2 protein is a radical storage device containing an iron center-generated tyrosyl free radical. Previous work has identified an RNR protein in yeast, Rnr4p, which is homologous to other R2 proteins but lacks a number of conserved amino acid residues involved in iron binding. Using highly purified recombinant yeast RNR proteins, we demonstrate that the crucial role of Rnr4p (beta') is to fold correctly and stabilize the radical-storing Rnr2p by forming a stable 1:1 Rnr2p/Rnr4p complex. This complex sediments at 5.6 S as a betabeta' heterodimer in a sucrose gradient. In the presence of Rnr1p, both polypeptides of the Rnr2p/Rnr4p heterodimer cosediment at 9.7 S as expected for an alpha(2)betabeta' heterotetramer, where Rnr4p plays an important role in the interaction between the alpha(2) and the betabeta ' subunits. The specific activity of the Rnr2p complexed with Rnr4p is 2,250 nmol deoxycytidine 5'-diphosphate formed per min per mg, whereas the homodimer of Rnr2p shows no activity. This difference in activity may be a consequence of the different conformations of the inactive homodimeric Rnr2p and the active Rnr4p-bound form, as shown by CD spectroscopy. Taken together, our results show that the Rnr2p/Rnr4p heterodimer is the active form of the yeast RNR small subunit.
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| 15. |
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| 17. |
- Hillerich, Karla, et al.
(författare)
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Cu particle seeded InP InAs axial nanowire heterostructures
- 2013
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Ingår i: Physica Status Solidi. Rapid Research Letters. - : Wiley. - 1862-6254. ; 7:10, s. 850-854
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the epitaxial growth of alternating InP-InAs nanowire heterostructures using Cu seed particles in MOVPE. We observe extraordinary early stages in the formation of InAs segments, e.g. three-dimensional nucleation instead of step-flow growth. Furthermore, InAs segments of thin nanowires exhibit extended 4H crystal structure.
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| 18. |
- Ismail, S, et al.
(författare)
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Direct observation of the molten state of nanometer-sized particles with an atomic force microscope: A feasibility study
- 2002
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Ingår i: Journal of Nanoparticle Research. - 1572-896X. ; 4:4, s. 351-356
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Tidskriftsartikel (refereegranskat)abstract
- An atomic force microscope (AFM) was used to directly examine the physical state of nanometer-sized particles. The critical diameter of indium particles, where evidence of melting at room temperature was observed, was 7.8 +/- 1.2 nm. This conclusion is based on a method relying on the manipulation of particles in ambient air and at constant temperature. This method involves a simple set-up that permits a combination of both manipulation and imaging of individual particles. To determine whether a particle is molten, three criteria are used: the merging of particles to form bigger spherical particles, a tip-induced shape change, and the formation of nanofibers. All three criteria have been checked using other particle materials. An attempt at 56degreesC revealed oxidation of the indium particles as the major problem for melting investigation. Manipulations under high-purity nitrogen atmosphere support the validity of the findings. The use of the AFM to determine whether a nanoparticle is molten is, however, complicated by the oxidation issue.
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| 19. |
- Johannes, A., et al.
(författare)
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Enhanced sputtering and incorporation of Mn in implanted GaAs and ZnO nanowires
- 2014
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Ingår i: Journal of Physics D: Applied Physics. - Bristol : IOP Publishing. - 1361-6463 .- 0022-3727. ; 47:39
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Tidskriftsartikel (refereegranskat)abstract
- We simulated and experimentally investigated the sputter yield of ZnO and GaAs nanowires, which were implanted with energetic Mn ions at room temperature. The resulting thinning of the nanowires and the dopant concentration with increasing Mn ion fluency were measured by accurate scanning electron microscopy (SEM) and nano-x-Ray Fluorescence (nanoXRF) quantification, respectively. We observed a clearly enhanced sputter yield for the irradiated nanowires compared to bulk, which is also corroborated by iradina simulations. These show a maximum if the ion range matches the nanowire diameter. As a consequence of the erosion thinning of the nanowire, the incorporation of the Mn dopants is also enhanced and increases non-linearly with increasing ion fluency.
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| 20. |
- Kortegaard, Carl, et al.
(författare)
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Observation of the molten state of nano-particles with an atomic force microscope
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- An atomic force microscope was used to directly examine the physical state of nanometer-sized particles. The critical diameter of indium particles, where evidence of melting at room temperature was observed, was 7.8±1.2 nm. This conclusion is based on a method relying on the manipulation of particles in ambient air and at constant temperature. This method involves a simple set up that permits a combination of both manipulation and imaging of individual particles. To determine whether a particle is molten, three criteria are used: the merging of particles to form bigger spherical particles, a tip-induced shape change and the formation of nanofibres. All three criteria have been checked using other particle materials. The use of the atomic force microscope to determine whether a nanoparticle is molten, is however complicated by oxidation
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| 23. |
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| 25. |
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| 26. |
- Plissard, S., et al.
(författare)
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Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 96:12
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Tidskriftsartikel (refereegranskat)abstract
- Growth of GaAs/GaAsSb heterostructure nanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAs nanowires is first obtained, and then GaAsxSb1-x segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAs nanowire and passivated using an AlxGa1-xAs shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.
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| 27. |
- Potts, H., et al.
(författare)
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Electrical control of spins and giant g-factors in ring-like coupled quantum dots
- 2019
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Emerging theoretical concepts for quantum technologies have driven a continuous search for structures where a quantum state, such as spin, can be manipulated efficiently. Central to many concepts is the ability to control a system by electric and magnetic fields, relying on strong spin-orbit interaction and a large g-factor. Here, we present a mechanism for spin and orbital manipulation using small electric and magnetic fields. By hybridizing specific quantum dot states at two points inside InAs nanowires, nearly perfect quantum rings form. Large and highly anisotropic effective g-factors are observed, explained by a strong orbital contribution. Importantly, we find that the orbital contributions can be efficiently quenched by simply detuning the individual quantum dot levels with an electric field. In this way, we demonstrate not only control of the effective g-factor from 80 to almost 0 for the same charge state, but also electrostatic change of the ground state spin.
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| 28. |
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| 29. |
- Skårman, B, et al.
(författare)
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Evaluation of intermittent contact mode AFM probes by HREM and using atomically sharp CeO2 ridges as tip characterizer
- 2000
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 16:15, s. 6267-6277
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Tidskriftsartikel (refereegranskat)abstract
- The imaging process of the atomic force microscope (AFM) in contact, noncontact, and intermittent contact mode is still debated after more than a decade of widespread use, in particular when imaged features are approaching atomic dimensions. Several models for the interaction between the tip and the surface have been suggested, but generally they all need an exact description of the geometry of either the tip, the surface, or both. We present here a tip characterizer with close to reproducible geometry, exactly known angles of all surfaces, and sharp features with close to atomic dimension. It has been tested on three commercial AFM probes and a laboratory-made electron-beam-deposited tip, sharpened by oxygen plasma etching. High-resolution transmission electron microscopy has been used to unambiguously verify the tip shapes down to atomic dimensions, both before and after imaging in intermittent contact mode. The effect on the recorded AFM images is shown of tip shape, tip wear, spallation, and accumulation on the tip of amorphous and crystalline debris. The imaging is shown to be a dynamic event, with a continuously changing tip and occasional catastrophic events that give abrupt changes in imaging conditions. The tips are severely worn down already after scanning a few centimeters, but accumulated amorphous material may still give it imaging capabilities in the nanometer range, even with having a tip radius exceeding 130 nm. Accumulated amorphous material seems to be more important than previously believed. Procedures for tip in situ characterization and reliable imaging are suggested.
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| 30. |
- Thelander, Claes, et al.
(författare)
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Nanowire-based one-dimensional electronics
- 2006
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Ingår i: Materials Today. - 1369-7021. ; 9:10, s. 28-35
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Tidskriftsartikel (refereegranskat)abstract
- During the last half century, a dramatic downscaling of electronics has taken place, a miniaturization that the industry expects to continue for at least a decade. We present efforts to use the self-assembly of one-dimensional semiconductor nanowires(1) in order to bring new, high-performance nanowire devices as an add-on to mainstream Si technology. The nanowire approach offers a coaxial gate-dielectric-channel geometry that is ideal for further downscaling and electrostatic control, as well as heterostructure-based devices on Si wafers.
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| 31. |
- Ungerer, J. H., et al.
(författare)
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Strong coupling between a microwave photon and a singlet-triplet qubit
- 2024
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Ingår i: Nature Communications. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Combining superconducting resonators and quantum dots has triggered tremendous progress in quantum information, however, attempts at coupling a resonator to even charge parity spin qubits have resulted only in weak spin-photon coupling. Here, we integrate a zincblende InAs nanowire double quantum dot with strong spin-orbit interaction in a magnetic-field resilient, high-quality resonator. The quantum confinement in the nanowire is achieved using deterministically grown wurtzite tunnel barriers. Our experiments on even charge parity states and at large magnetic fields, allow us to identify the relevant spin states and to measure the spin decoherence rates and spin-photon coupling strengths. We find an anti-crossing between the resonator mode in the single photon limit and a singlet-triplet qubit with a spin-photon coupling strength of g/2π = 139 ± 4 MHz. This coherent coupling exceeds the resonator decay rate κ/2π = 19.8 ± 0.2 MHz and the qubit dephasing rate γ/2π = 116 ± 7 MHz, putting our system in the strong coupling regime.
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| 32. |
- Vasen, T., et al.
(författare)
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InAs nanowire GAA n-MOSFETs with 12-15 nm diameter
- 2016
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Ingår i: 2016 IEEE Symposium on VLSI Technology, VLSI Technology 2016. - 9781509006373 ; 2016-September
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Konferensbidrag (refereegranskat)abstract
- InAs nanowires (NW) grown by MOCVD with diameter d as small as 10 nm and gate-All-Around (GAA) MOSFETs with d = 12-15 nm are demonstrated. Ion = 314 μA/μm, and Ssat =68 mV/dec was achieved at Vdd = 0.5 V (Ioff = 0.1 μA/μm). Highest gm measured is 2693 μS/μm. Device performance is enabled by small diameter and optimized high-k/InAs gate stack process. Device performance tradeoffs between gm, Ron, and Imin are discussed.
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| 33. |
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| 34. |
- Wiese Simonsen, K, et al.
(författare)
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Fatal poisoning in drug addicts in the Nordic countries in 2007
- 2011
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Ingår i: FORENSIC SCIENCE INTERNATIONAL. - : Elsevier Science B.V., Amsterdam.. - 0379-0738. ; 207:1-3, s. 170-176
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Tidskriftsartikel (refereegranskat)abstract
- The frequency of medico-legally examined fatal poisonings in 2007 among drug addicts was investigated in five Nordic countries; Denmark, Finland, Iceland, Norway, and Sweden. The number of deaths, age, sex, place of death, main intoxicant, and other drugs present in blood samples were recorded to obtain national and comparable Nordic data, as well as data to compare with earlier studies in 2002, 1997, and 1991. Norway had the highest incidence of drug addict deaths by poisoning followed by Denmark, with 8.24 and 6.92 per 100,000 inhabitants, respectively. The death rates in Finland (4.02), Iceland (4.56), and Sweden (3.53) were about half that of Norway and Denmark. Compared with earlier studies, the death rates were unchanged in Denmark and Norway, but increased in Finland, Iceland, and Sweden. In all countries, fewer deaths (29-35%) were recorded in the capital area compared with earlier studies. Females accounted for 11-19% of the fatal poisonings. Iceland deviates with a more equal distribution between men and women (40%). Deaths from methadone overdoses increased in all Nordic countries, and methadone was the main intoxicant in Denmark in 2007, accounting for 51% of the poisonings. In Norway and Sweden, heroin/morphine was still the main intoxicant with a frequency of 68% and 48%, respectively. In Iceland, 3 deaths each were due to heroin/morphine and methadone, respectively. Finland differs from other Nordic countries in having a high number of poisonings caused by buprenorphine and very few caused by heroin/morphine. The total number of buprenorphine deaths in Finland doubled from 16 in 2002 to 32 in 2007, where it constituted 25% of deaths. The general toxicological screening program showed widespread multi-drug use in all countries. The median number of drugs per case varied from 3 to 5. The most frequently detected substances were heroin/morphine, methadone, buprenorphine, tramadol, amphetamine, cocaine, tetrahydrocannabinol, benzodiazepines and ethanol. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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