| 31. |
- Graczyk, Mariusz, et al.
(författare)
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Optimization of a self-closing effect to produce nanochannels with top slits in fused silica
- 2012
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Ingår i: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 30:6
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on the fabrication of subsurfaced 100-600 nm wide nanochannels in fused silica with top slit openings in the size range of 5-10 nm. Such nanochannels can be used in combination with a nanofluidics system to guide molecular motors and quickly switch the chemical environment inside the nanochannels through diffusion via the top slits. To realize nanochannel top slits in this size range, the authors here demonstrate the use of a self-closing effect based on the volume expansion of a thin Si layer during oxidation. A high contrast electron beam lithography exposure step in conjunction with dry etching of SiO2 by reactive ion etching (RIE) and Si by inductively coupled plasma-RIE followed by wet etching of a fused silica substrate is used to create the initial slit before oxidation. The details of nanochannel fabrication steps are described and discussed. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.4766317]
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| 32. |
- Gustafsson, Anders, et al.
(författare)
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Reevaluation of blueshifts introduced by lateral confinement in quantum-well wire structures
- 1993
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Ingår i: Applied Physics Letters. - 0003-6951. ; 12:15, s. 1709-1711
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Tidskriftsartikel (refereegranskat)abstract
- The luminescence from etched quantum-well wire structures often exhibits an unexpectedly large blueshift of the peak energy position. Further, the shift is usually quite independent of the width of the wires. In this letter we show that this blueshift can be explained as a decreased transfer of excitons between areas of different monolayer thicknesses within the single quantum wells, caused by a change in the exciton diffusion from being two-dimensional in the quantum wells to one-dimensional in the wires. This reduced transfer will result in a blueshift of the peak energy position if the monolayer splitting is unresolved.
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| 33. |
- Harb, Maher, et al.
(författare)
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The c-axis thermal conductivity of graphite film of nanometer thickness measured by time resolved X-ray diffraction
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:23
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the use of time resolved X-ray diffraction to measure the dynamics of strain in laser-excited graphite film of nanometer thickness, obtained by chemical vapour deposition (CVD). Heat transport in the CVD film is simulated with a 1-dimensional heat diffusion model. We find the experimental data to be consistent with a c-axis thermal conductivity of similar to 0.7 Wm(-1) K-1. This value is four orders of magnitude lower than the thermal conductivity in-plane, confirming recent theoretical calculations of the thermal conductivity of multilayer graphene. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769214]
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| 34. |
- Jafari Jam, Reza, et al.
(författare)
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III-V nanowire synthesis by use of electrodeposited gold particles
- 2015
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Ingår i: Nano letters (Print). - Washington, DC : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 15:1, s. 134-138
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires are great candidates for building novel electronic devices. Considering the cost of fabricating such devices, substrate reuse and gold consumption are the main concerns. Here we report on implementation of high throughput gold electrodeposition for selective deposition of metal seed particles in arrays defined by lithography for nanowire synthesis. By use of this method, a reduction in gold consumption by a factor of at least 300 was achieved, as compared to conventional thermal evaporation for the same pattern. Because this method also facilitates substrate reuse, a significantly reduced cost of the final device is expected. We investigate the morphology, crystallography, and optical properties of InP and GaAs nanowires grown from electrodeposited gold seed particles and compare them with the properties of nanowires grown from seed particles defined by thermal evaporation of gold. We find that nanowire synthesis, as well as the material properties of the grown nanowires are comparable and quite independent of the gold deposition technique. On the basis of these results, electrodeposition is proposed as a key technology for large-scale fabrication of nanowire-based devices.
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| 35. |
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| 36. |
- Joensson, C T, et al.
(författare)
-
Synthesis and characterization of cobalt silicide films on silicon
- 2006
-
Ingår i: Ion Beam Analysis - Proceedings of the Seventeenth International Conference on Ion Beam Analysis (Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms). - : Elsevier BV. - 0168-583X. ; 249, s. 532-535
-
Konferensbidrag (refereegranskat)abstract
- Cobalt silicide has emerged as a leading contact material in silicon technology due to its low resistivity, high stability and small lattice mismatch. In this study, 0.2-0.4 mu m thick Co films were deposited on Si(100) wafers by RF magnetron sputtering at room temperature, and annealed at temperatures from 600 to 900 degrees C in vacuum. As-deposited and annealed samples were characterized by Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Although the Si substrates were sputter cleaned before the deposition, all the samples showed a thin oxide layer at the Si/Co interfaces. Annealing up to 700 degrees C did not alter the composition at the interface except small amount Co diffusion into Si. Annealing at 800 degrees C promotes the evaporation of the oxides from the interface and, as a result, clean CoSi2 films were formed. Although the interface appeared to be sharp within the RBS resolution after high temperature annealing, the surface topography was relatively rough with varying size of crystal grains. (c) 2006 Elsevier B.V. All rights reserved.
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| 37. |
- Khan, Sabbir Ahmed, et al.
(författare)
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High-Definition Nanoimprint Stamp Fabrication by Atomic Layer Etching
- 2018
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; , s. 2476-2482
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: Nanoimprint lithography (NIL) has the potential for low-cost andhigh-throughput nanoscale fabrication. However, the NIL quality and resolution areusually limited by the shape and size of the nanoimprint stamp features. Atomiclayer etching (ALE) can provide a damage-free pattern transfer with ultimate etchcontrol for features of all length scales, down to the atomic scale, and for all featuregeometries, which is required for good quality and high-resolution nanoimprintstamp fabrication. Here, we present an ALE process for nanoscale pattern transferand high-resolution nanoimprint stamp preparation. This ALE process is based onchemical adsorption of a monoatomic layer of dichloride (Cl2) on the siliconsurface, followed by the removal of a monolayer of Cl2-modified silicon by argonbombardment. The nanopatterns of different geometries, loadings, and pitcheswere fabricated by electron beam lithography on a silicon wafer, and ALE wassubsequently performed for pattern transfer using a resist as an etch mask. Thepost-ALE patterns allowed us to study the different effects and limitations of theprocess, such as trenching and sidewall tapering. The ALE-processed silicon wafers were used as hard nanoimprint stamps in a thermal nanoimprint process. Features as small as 30 nm were successfully transferred into a poly(methyl methacrylate) layer, which demonstrated the great potential of ALE in fabricating nanoimprint stamps with ultrahigh resolution.
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| 38. |
- Koksharov, Yu.A., et al.
(författare)
-
Magnetostatic interactions in planar ring-like nanoparticle structures
- 2006
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 515, s. 731-734
-
Tidskriftsartikel (refereegranskat)abstract
- Numerical calculations of equilibrium state energies and local magnetic fields in planar ring-like nanoparticle structures were performed. The dipole–dipole, Zeeman and magnetic anisotropy interactions were included into the model. The result of their competition depends on the value of the external magnetic field, magnetic parameters of an individual nanoparticle, size and shape of the structures. Flux-closed vortexes, single domain, two- domain ‘‘onion’’-like, ‘‘hedgehog’’-like and more complex spin structures can be realized. The critical field, providing a sharp transition from the flux-closed vortex to the ‘‘onion’’-like state, can be regulated by a variation of the particle magnetization and anisotropy constant, their easy directions, and particle space arrangement.
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| 39. |
- Lindberg, Frida W., et al.
(författare)
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Design and development of nanoimprint-enabled structures for molecular motor devices
- 2019
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Ingår i: Materials Research Express. - : IOP Publishing. - 2053-1591. ; 6:2
-
Tidskriftsartikel (refereegranskat)abstract
- Devices based on molecular motor-driven cytoskeletal filaments, e.g., actin filaments, have been developed both for biosensing and biocomputational applications. Commonly, these devices require nanoscaled tracks for guidance of the actin filaments which has limited the patterning technique to electron beam lithography. Thus, large scale systems become intractable to fabricate at a high throughput within a reasonable time-frame. We have studied the possibility to fabricate molecular motor-based devices using the high throughput, high resolution technique of nanoimprint lithography. Molecular motor-based devices require wide open regions (loading zones) to allow filaments to land for later propulsion into the nanoscale tracks. Such open zones are challenging to fabricate using nanoimprint lithography due to the large amount of material displaced in the process. We found that this challenge can be overcome by introducing nanoscaled pillars inside the loading zones, into which material can be displaced during imprint. By optimising the resist thickness, we were able to decrease the amount of material displaced without suffering from insufficient filling of the stamp. Furthermore, simulations suggest that the shape and positioning of the pillars can be used to tailor the overall cytoskeletal filament transportation direction and behaviour. This is a potentially promising design feature for future applications that however, requires further optimisations before experimental realisation.
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| 40. |
- Lu, Fangchao, et al.
(författare)
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Enhanced Anisotropic Effective g Factors of an Al10.25Ga0.75N/GaN Heterostructure Based Quantum Point Contact
- 2013
-
Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4654-4658
-
Tidskriftsartikel (refereegranskat)abstract
- Gate-defined quantum point contacts (QPCs) were fabricated with Al0.25Ga0.75N/GaN heterostructures grown by metal organic chemical Vapor deposition (MOCVD). In the transport study of the Zeeman effect, greatly enhanced effective g factors (g*).were obtained. The in-plane g* is found to be 5.5 +/- 0.6, 4.8 0.4, and 4.2 0.4 for the first to the third subband, respectively. Similarly, the out-of-plane g* is 8.3 0.6, 6.7 0.7, and 5.1 0.7. Increasing g* with the population of odd-numbered spin-splitted subbands are obtabed at 14 T. This portion of increase is assumed to arise from the exchange interaction in one-dimensional systems. A careful analysis shows that not only the exchange interaction but the spin orbit interaction (SOI) in the strongly confined QPC contribunts to the enhancement and anisotropy of g* in different subbands. An approach to distinguish the respective contributions from the SOI and exchange interaction is therefore proposed.
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