| 21. |
- Liu, Ruisheng, et al.
(författare)
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Large magnetoresistance in Co/Ni/Co ferromagnetic single electron transistors
- 2007
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Ingår i: Applied Physics Letters. - New York : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 90:12, s. 123111-
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on magnetotransport investigations of nanoscaled ferromagnetic Co/Ni/Co single electron transistors. As a result of reduced size, the devices exhibit single electron transistor characteristics at 4.2 K. Magnetotransport measurements carried out at 1.8 K reveal tunneling magnetoresistance (TMR) traces with negative coercive fields, which the authors interpret in terms of a switching mechanism driven by the shape anisotropy of the central wirelike Ni island. A large TMR of about 18% is observed within a finite source-drain bias regime. The TMR decreases rapidly with increasing bias, which the authors tentatively attribute to excitation of magnons in the central island.
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| 22. |
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| 23. |
- Liu, Ruisheng, et al.
(författare)
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Nanoscaled ferromagnetic single electron transistors
- 2007
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Ingår i: [Host publication title missing]. - Piscataway, N.J. : IEEE Press. ; 1-3, s. 420-423, s. 420-421
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report on a summary of fabricating and characterizing nanoscaled ferromagnetic single-electron transistors (F-SETs). One type of device is assembled with an atomic force microscope. A single 30 nm Au disc, forming the central island of the transistor, is manipulated with Angstrom precision into the gap between plasma oxidized Ni source and drain electrodes which are designed with different geometries to facilitate magnetic moment reversal at different magnetic fields. The tunnel resistances can be tuned in real-time during the device fabrication by re-positioning the An disc. A second type of device with Co electrodes and a central Au island is fabricated using a high-precision alignment procedure invoked during e-beam writing. Both devices exhibit single-electron transistor characteristics at 4.2K. From magnetotransport measurements carried out at 1.7K, we found that it is more efficient to realize spin injection and detection in Co/Au/Co devices fabricated with the second technique. A maximum TMR of about 4% was observed in these devices.
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| 24. |
- Nebol'sin, Valery A., et al.
(författare)
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Capillary stability of vapor-liquid-solid crystallization processes and their comparison to Czochralski and Stepanov growth methods
- 2017
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 463, s. 46-53
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial semiconductor nanowires grown with vapor-liquid-solid crystallization processes are very attractive nanoscale objects for many different applications. Despite extensive studies of the growth mechanism, there is still a lack of understanding of the growth process; in particular, the stability of the vapor-liquid-solid crystallization process has not previously been studied. Here we examine the capillary stability of the vapor-liquid-solid growth of nanowires and filamentary crystals with different diameters and demonstrate that the growth is stable for small Bond numbers when the meniscus height is linearly dependent on catalyst diameter. The capillary stability of vapor-liquid-solid growth is also compared with capillary stability in the Stepanov and Czochralski crystal growth methods; it is shown that capillary stability is not possible in the Czochralski method, although it is possible in the Stepanov growth method when the ratio of crystal diameter to shaper diameter is >1/2. These findings are important for better understanding and improved control of the growth of nanowires and filamentary crystals and indicate, for example, that large diameter filamentary crystals can be grown via a vapor-liquid-solid mechanism if the influence of gravity forces on the liquid catalytic particle shape can be reduced.
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| 25. |
- Nebol'sin, Valery A., et al.
(författare)
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Thermodynamics of oxidation and reduction during the growth of metal catalyzed silicon nanowires
- 2019
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 505, s. 52-58
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the thermodynamics of oxide formation, and the recovery of silicon and the metal catalysts from the dissociation of their respective oxides during the growth process of Si nanowires (NWs) under the Vapor → Liquid Droplet → Solid (VLS) mechanism. It is demonstrated that Si NWs under growth temperatures are thermodynamically unstable in any gas phase containing even a small concentration of O2, and under favorable kinetic conditions Si NWs should entirely convert into dioxide (SiO2). Thermal dissociation of SiO2 in the growth conditions for NWs is practically impossible as it would require either lowering the pressure of O2 to an unachievable, critically low value or raising the temperature to a point which is impossible to reach in ordinary conditions. Decreasing the diameter, i.e., increasing the Si NW dispersity, leads to an increase in the interaction with O2 and this O2 will be held more tightly by Si. Thus, thinner NWs should oxidize stronger than thicker ones. The main metal catalysts for NW growth, as well as Si, are characterized by significant affinity with O2 and inconvertible oxide formation reactions. The most stable Si NW growth is observed with metals (Au, Pt, Cu, Ni, etc.) whose oxides are less stable than SiO2. Only metals with a lower affinity to O2 than to H2 or any other reducing agent are applicable to guarantee the recovery process when used as a catalyst for the growth of NWs.
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| 26. |
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| 27. |
- Pettersson, H., et al.
(författare)
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Assembling Ferromagnetic Single-electron Transistors with Atomic Force Microscopy
- 2008
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Ingår i: Nanostructures in electronics and photonics. - London : Pan Stanford Publishing. - 9789814241106 - 9789814241120 ; , s. 29-40
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Bokkapitel (refereegranskat)abstract
- Ferromagnetic Single Electron Transistors (F-SETs) comprise ferromagnetic electrodes connected to a ferromagnetic- or non-magnetic central island via tunnel barriers. These devices are important for studies of spin-transport physics in confined structures. Here we describe the development of a novel type of AFM-assembled nano-scale F-SETs suitable for spin-transport investigations at temperatures above 4.2 K. The ingenious fabrication technique means that their electrical characteristics can be tuned in real-time during the fabrication sequence by re-positioning the central island with Ångström precision.
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| 28. |
- Pettersson, Håkan, 1962-, et al.
(författare)
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Assembling ferromagnetic single-electron transistors with atomic force microscopy
- 2016. - 2
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Ingår i: Nanostructures in Electronics and Photonics. - London : Pan Stanford Publishing. - 9789814241120 - 9789814241106 ; , s. 29-40
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Ferromagnetic Single Electron Transistors (F-SETs) comprise ferromagnetic electrodes connected to a ferromagnetic- or non-magnetic central island via tunnel barriers. These devices are important for studies of spin-transport physics in confined structures. Here we describe the development of a novel type of AFMassembled nano-scale F-SETs suitable for spin-transport investigations at temperatures above 4.2 K. The ingenious fabrication technique means that their electrical characteristics can be tuned in real-time during the fabrication sequence by re-positioning the central island with Ångström precision. © 2008 by Taylor & Francis Group, LLC.
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| 29. |
- Pettersson, Håkan, 1962-, et al.
(författare)
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Nano-Schottky contacts realized by bottom-up technique
- 2010
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Ingår i: Bulletin of American Physical Society. - : American Physical Society.
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Konferensbidrag (refereegranskat)abstract
- Here we present a comprehensive study of a rectifying nano-Schottky contact formed at the interface between a gold catalytic particle and an epitaxially grown GaInAs/InAs nanowire. Selective electrical connections formed by electron beam lithography to the catalytic particle on one side, and to the InAs segment on the other side allowed electrical and optical characterization of the formed Schottky junction. From IV measurements taken at different temperatures we have deduced the Schottky barrier height and the height of the barrier formed in the graded GaInAs nanowire segment. The IV characteristics measured under laser stimulation showed that the device can be used as a unipolar photodetector with extremely small detection volume and potentially ultra fast response.
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| 30. |
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