| 1. |
- Scannell, B. C., et al.
(författare)
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Probing the sensitivity of electron wave interference to disorder-induced scattering in solid-state devices
- 2012
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 85:19
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Tidskriftsartikel (refereegranskat)abstract
- The study of electron motion in semiconductor billiards has elucidated our understanding of quantum interference and quantum chaos. The central assumption is that ionized donors generate only minor perturbations to the electron trajectories, which are determined by scattering from billiard walls. We use magnetoconductance fluctuations as a probe of the quantum interference and show that these fluctuations change radically when the scattering landscape is modified by thermally induced charge displacement between donor sites. Our results challenge the accepted understanding of quantum interference effects in nanostructures.
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| 2. |
- Carrad, D J, et al.
(författare)
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Hybrid Nanowire Ion-to-Electron Transducers for Integrated Bioelectronic Circuitry
- 2017
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:2, s. 827-833
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Tidskriftsartikel (refereegranskat)abstract
- A key task in the emerging field of bioelectronics is the transduction between ionic/protonic and electronic signals at high fidelity. This is a considerable challenge since the two carrier types exhibit intrinsically different physics and are best supported by very different materials types - electronic signals in inorganic semiconductors and ionic/protonic signals in organic or bio-organic polymers, gels, or electrolytes. Here we demonstrate a new class of organic-inorganic transducing interface featuring semiconducting nanowires electrostatically gated using a solid proton-transporting hygroscopic polymer. This model platform allows us to study the basic transducing mechanisms as well as deliver high fidelity signal conversion by tapping into and drawing together the best candidates from traditionally disparate realms of electronic materials research. By combining complementary n- and p-type transducers we demonstrate functional logic with significant potential for scaling toward high-density integrated bioelectronic circuitry.
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| 3. |
- Martin, T. P., et al.
(författare)
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Enhanced Zeeman splitting in Ga0.25In0.75As quantum point contacts
- 2008
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 93:1
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Tidskriftsartikel (refereegranskat)abstract
- The strength of the Zeeman splitting induced by an applied magnetic field is an important factor for the realization of spin-resolved transport in mesoscopic devices. We measure the Zeeman splitting for a quantum point contact etched into a Ga0.25In0.75As quantum well, with the field oriented parallel to the transport direction. We observe an enhancement of the Lande g-factor from vertical bar g*vertical bar=3.8 +/- 0.2 for the third subband to vertical bar g*vertical bar=5.8 +/- 0.6 for the first subband, six times larger than in GaAs. We report subband spacings in excess of 10 meV, which facilitates quantum transport at higher temperatures. (C) 2008 American Institute of Physics.
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| 4. |
- Martin, T. P., et al.
(författare)
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Field-orientation dependence of the Zeeman spin splitting in (In,Ga)As quantum point contacts
- 2010
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 81:4
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Tidskriftsartikel (refereegranskat)abstract
- We study the Zeeman spin splitting in a quantum point contact (QPC) etched into an InGaAs/InP heterostructure for three orthogonal magnetic field orientations with respect to the QPC. For the two in-plane orientations we observe an isotropic Zeeman spin splitting, which becomes stronger as the system is made more one dimensional. The Lande g factor is enhanced by up to a factor of two compared to two-dimensional electron systems in InGaAs/InP. A much larger Zeeman splitting is observed when the field is oriented perpendicular to the heterostructure, resulting in a g factor of 15.7 in the one-dimensional limit.
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| 5. |
- Micolich, A. P., et al.
(författare)
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Is it the boundaries or disorder that dominates electron transport in semiconductor `billiards'?
- 2013
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Ingår i: Fortschritte der Physik. - : Wiley. - 0015-8208. ; 61:2-3, s. 332-347
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Forskningsöversikt (refereegranskat)abstract
- Semiconductor billiards are often considered as ideal systems for studying dynamical chaos in the quantum mechanical limit. In the traditional picture, once the electron's mean free path, as determined by the mobility, becomes larger than the device, disorder is negligible and electron trajectories are shaped by specular reflection from the billiard walls alone. Experimental insight into the electron dynamics is normally obtained by magnetoconductance measurements. A number of recent experimental studies have shown these measurements to be largely independent of the billiard's exact shape, and highly dependent on sample-to-sample variations in disorder. In this paper, we discuss these more recent findings within the full historical context of work on semiconductor billiards, and offer strong evidence that small-angle scattering at the sub-100 nm length-scale dominates transport in these devices. This has important implications for the role these devices can play for experimental tests of ideas in quantum chaos. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 6. |
- Gluschke, J. G., et al.
(författare)
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Integrated bioelectronic proton-gated logic elements utilizing nanoscale patterned Nafion
- 2021
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Ingår i: Materials Horizons. - : Royal Society of Chemistry (RSC). - 2051-6347 .- 2051-6355. ; 8:1, s. 224-233
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Tidskriftsartikel (refereegranskat)abstract
- A central endeavour in bioelectronics is the development of logic elements to transduce and process ionic to electronic signals. Motivated by this challenge, we report fully monolithic, nanoscale logic elements featuring n- and p-type nanowires as electronic channels that are proton-gated by electron-beam patterned Nafion. We demonstrate inverter circuits with state-of-the-art ion-to-electron transduction performance giving DC gain exceeding 5 and frequency response up to 2 kHz. A key innovation facilitating the logic integration is a new electron-beam process for patterning Nafion with linewidths down to 125 nm. This process delivers feature sizes compatible with low voltage, fast switching elements. This expands the scope for Nafion as a versatile patternable high-proton-conductivity element for bioelectronics and other applications requiring nanoengineered protonic membranes and electrodes.
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| 7. |
- Gluschke, J. G., et al.
(författare)
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Achieving short high-quality gate-all-around structures for horizontal nanowire field-effect transistors
- 2018
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 30:6
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Tidskriftsartikel (refereegranskat)abstract
- We introduce a fabrication method for gate-all-around nanowire field-effect transistors. Single nanowires were aligned perpendicular to underlying bottom gates using a resist-trench alignment technique. Top gates were then defined aligned to the bottom gates to form gate-all-around structures. This approach overcomes significant limitations in minimal obtainable gate length and gate-length control in previous horizontal wrap-gated nanowire transistors that arise because the gate is defined by wet-etching. In the method presented here gate-length control is limited by the resolution of the electron-beam-lithography process. We demonstrate the versatility of our approach by fabricating a device with an independent bottom gate, top gate, and gate-all-around structure as well as a device with three independent gate-all-around structures with 300, 200, and 150 nm gate length. Our method enables us to achieve subthreshold swings as low as 38 mV dec-1 at 77 K for a 150 nm gate length.
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| 8. |
- Miranda, M. Sanchez, et al.
(författare)
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Prospects for single-molecule electrostatic detection in molecular motor gliding motility assays
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:6
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Tidskriftsartikel (refereegranskat)abstract
- Molecular motor gliding motility assays based on myosin/actin or kinesin/microtubules are of interest for nanotechnology applications ranging from cargo-trafficking in lab-on-a-chip devices to novel biocomputation strategies. Prototype systems are typically monitored by expensive and bulky fluorescence microscopy systems. The development of integrated, direct electric detection of single filaments would strongly benefit applications and scale-up. We present estimates for the viability of such a detector by calculating the electrostatic potential change generated at a carbon nanotube transistor by a motile actin filament or microtubule under realistic gliding assay conditions. We combine this with detection limits based on previous state-of-the-art experiments using carbon nanotube transistors to detect catalysis by a bound lysozyme molecule and melting of a bound short-strand DNA molecule. Our results show that detection should be possible for both actin and microtubules using existing low ionic strength buffers given good device design, e.g., by raising the transistor slightly above the guiding channel floor. We perform studies as a function of buffer ionic strength, height of the transistor above the guiding channel floor, presence/absence of the casein surface passivation layer for microtubule assays and the linear charge density of the actin filaments/microtubules. We show that detection of microtubules is a more likely prospect given their smaller height of travel above the surface, higher negative charge density and the casein passivation, and may possibly be achieved with the nanoscale transistor sitting directly on the guiding channel floor.
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| 9. |
- Travaglini, L., et al.
(författare)
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Single-Material OECT-Based Flexible Complementary Circuits Featuring Polyaniline in Both Conducting Channels
- 2020
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Ingår i: Advanced Functional Materials. - : Wiley-VCH Verlagsgesellschaft. - 1616-301X .- 1616-3028.
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Tidskriftsartikel (refereegranskat)abstract
- The organic electrochemical transistor (OECT) with a conjugated polymer as the active material is the elementary unit of organic bioelectronic devices. Improved functionalities, such as low power consumption, can be achieved by building complementary circuits featuring two or more OECTs. Complementary circuits commonly combine both p- and n-type transistors to reduce power draw. While p-type OECTs are readily available, n-type OECTs are less common mainly due to poor stability of the n-type active channel material in aqueous electrolyte. Here, a complementary circuit is made using a pair of OECTs having polyaniline (PANI) as the channel material in both transistors. PANI, with a finite electrochemical window accessible at voltages lower than 1 V, exhibits a peak in current versus gate voltage when used as an active channel in an OECT. The current peak has two slopes, one n-like and one p-like, which correspond to different electrochemical regimes of the same underlying conjugated polymer. The electrochemistry enables the design of a complementary circuit using only PANI as the channel material. The PANI-based circuit is shown to have excellent performance with gain of ≈7 and is transferred on a flexible biocompatible chitosan substrate with demonstrated operation in aqueous electrolyte.
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| 10. |
- Burke, Adam, et al.
(författare)
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InAs Nanowire Transistors with Multiple, Independent Wrap-Gate Segments.
- 2015
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 15:5, s. 2836-2843
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Tidskriftsartikel (refereegranskat)abstract
- We report a method for making horizontal wrap-gate nanowire transistors with up to four independently controllable wrap-gated segments. While the step up to two independent wrap-gates requires a major change in fabrication methodology, a key advantage to this new approach, and the horizontal orientation more generally, is that achieving more than two wrap-gate segments then requires no extra fabrication steps. This is in contrast to the vertical orientation, where a significant subset of the fabrication steps needs to be repeated for each additional gate. We show that cross-talk between adjacent wrap-gate segments is negligible despite separations less than 200 nm. We also demonstrate the ability to make multiple wrap-gate transistors on a single nanowire using the exact same process. The excellent scalability potential of horizontal wrap-gate nanowire transistors makes them highly favorable for the development of advanced nanowire devices and possible integration with vertical wrap-gate nanowire transistors in 3D nanowire network architectures.
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