| 1. |
- Abdel, Naseem, et al.
(author)
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Fabrication and Characterization of Ultra-Thin PIN Silicon Detectors for Counting the Passage of MeV Ions
- 2013
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In: IEEE Transactions on Nuclear Science. - 0018-9499. ; 60:2, s. 1182-1188
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Journal article (peer-reviewed)abstract
- This paper describes the fabrication and initial characterization of an ultra-thin silicon PIN detector using a new technique in silicon nanotechnology. In collaboration with the Nuclear Physics Division and the Lund Nano Lab at Lund University, we have developed and manufactured ultra thin Delta E-detectors for spectroscopic applications. The fabrication process has been carried out using a double-polished silicon substrate n-type wafer and locally thinning by means of a 10:1 solution of 25% tetramethyl ammonium hydroxide (TMAH) with Isopropyl alcohol. More than 100 detectors of different thicknesses, down to 5 mu m with active areas ranging from 0.71 to 0.172 mm(2), have been fabricated. The main design considerations of our thin detectors were a very low leakage current below 12 nA and a low full depletion voltage at a reverse bias less than 1.5 V. Finally, most of our thin detectors offer an energy resolution (FWHM) as low as 31 keV for 5.487 MeV alpha particles from a Am-241 source.
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| 2. |
- Abdel, N. S., et al.
(author)
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Efficient ultra-thin transmission silicon detectors for a single-ion irradiation system at the Lund Ion Beam Analysis Facility
- 2014
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In: Journal of Instrumentation. - 1748-0221. ; 9
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Journal article (peer-reviewed)abstract
- This paper describes the fabrication of efficient ultra-thin silicon transmission detectors for use as pre-cell detectors in single-ion experiments on living cells at the Lund Ion Beam Analysis Facility. More than 40 detectors of different thicknesses down to 5 mu m have been fabricated and packaged. The main design considerations were very low leakage current (below 9 nA) and low full depletion voltage at biases less than 0.5 V at room temperature. In addition, we have shown that cooling the device can reduce the leakage current to 3 nA. The experimental testing of the pre-cell detection system is based on counting the passage of ions through the transmission (Delta E) detector before hitting the stopping (E) detector placed behind it, to ensure the accurate delivery of specific doses of radiation to the sample. Optimal detection of the fabricated detectors for the passage of an external beam of 2.2 MeV protons was obtained by cooling the device to below 2 degrees C. Cooling the Delta E detectors provides up to 20% better energy resolution and up to 98% detection efficiency for 2.2 MeV protons. The development of this kind of efficient pre-cell detector enables a range of new experiments to be conducted on thick biological samples.
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| 3. |
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| 4. |
- Graczyk, Mariusz, et al.
(author)
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Fabrication of bottle-shaped nanochannels in fused silica using a self-closing effect
- 2012
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In: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 97, s. 173-176
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Journal article (peer-reviewed)abstract
- The spatial control of molecular motor function, using nanostructured surfaces, is of great interest for the development of commercial devices for diagnostics and high-throughput drug screening with molecular motors as targets. In the present study we have fabricated 100-300 nm wide nanochannels, completely subsurfaced on fused silica chips, with the aim to interface them with a microfluidic system. Such a system will allow for changes in the chemical environment surrounding molecular motors, with minimal influence on their directional motion. This will be achieved by changing the chemical environment in a perpendicular direction to the motor motion and allowing the chemical substances to diffuse in and out of the nanochannels via a small slit (5-10 nm) on the top of the nanochannels. To create this slit, and to control its width, we here demonstrate the use of a self-closing effect based on the volume increase (2.27 times) during oxidation of silicon. The details of the fabrication steps (EBL, RIE and oxidation) are discussed. (C) 2012 Elsevier B.V. All rights reserved.
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| 5. |
- Graczyk, Mariusz, et al.
(author)
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Optimization of a self-closing effect to produce nanochannels with top slits in fused silica
- 2012
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In: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 30:6
-
Journal article (peer-reviewed)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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| 6. |
- Harb, Maher, et al.
(author)
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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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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:23
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Journal article (peer-reviewed)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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| 7. |
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| 8. |
- Lu, Fangchao, et al.
(author)
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Enhanced Anisotropic Effective g Factors of an Al10.25Ga0.75N/GaN Heterostructure Based Quantum Point Contact
- 2013
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4654-4658
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Journal article (peer-reviewed)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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| 9. |
- Meng, Fantao, et al.
(author)
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Efficient methods of nanoimprint stamp cleaning based on imprint self-cleaning effect.
- 2011
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In: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 22:18
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Journal article (peer-reviewed)abstract
- Nanoimprint lithography (NIL) is a nonconventional lithographic technique that promises low-cost, high-throughput patterning of structures with sub-10 nm resolution. Contamination of nanoimprint stamps is one of the key obstacles to industrialize the NIL technology. Here, we report two efficient approaches for removal of typical contamination of particles and residual resist from stamps: thermal and ultraviolet (UV) imprinting cleaning-both based on the self-cleaning effect of imprinting process. The contaminated stamps were imprinted onto polymer substrates and after demolding, they were treated with an organic solvent. The images of the stamp before and after the cleaning processes show that the two cleaning approaches can effectively remove contamination from stamps without destroying the stamp structures. The contact angles of the stamp before and after the cleaning processes indicate that the cleaning methods do not significantly degrade the anti-sticking layer. The cleaning processes reported in this work could also be used for substrate cleaning.
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| 10. |
- Meng, Fantao, et al.
(author)
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Fabrication and characterization of bilayer metal wire-grid polarizer using nanoimprint lithography on flexible plastic substrate
- 2011
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In: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 88:10, s. 3108-3112
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Journal article (peer-reviewed)abstract
- In this work, we demonstrate the fabrication of bilayer metal wire-grid polarizers and the characterization of their performance. The polarizers with 200 nm period were fabricated on flexible plastic substrates by nanoimprint lithography (NIL), followed by aluminum deposition. Transmission efficiency over 0.51 and extinction ratio higher than 950 can be achieved in the visible range when the aluminum thickness of the polarizer is 100 nm. The fabrication process only involves direct imprinting on flexible plastic substrates and aluminum deposition, without any resist spin-coating, lift-off, and etching processes, which is much simpler, less costly, and applicable to large volume production. (C) 2011 Elsevier B.V. All rights reserved.
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| 11. |
- Meng, Fantao, et al.
(author)
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Nonlinear electrical properties of Si three-terminal junction devices
- 2010
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:24
-
Journal article (peer-reviewed)abstract
- This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron transport in a three-terminal ballistic junction (TBJ) device. The results show that room temperature functional TBJ devices can be realized in a semiconductor material other than high-mobility III-V semiconductor heterostructures and provide a simple design principle for compact silicon devices in nanoelectronics. (C) 2010 American Institute of Physics. [doi:10.1063/1.3526725]
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| 12. |
- Pankratov, Dmitry, et al.
(author)
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The influence of nanoparticles on enzymatic bioelectrocatalysis
- 2014
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In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 4:72, s. 38164-38168
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Journal article (peer-reviewed)abstract
- In nearly all papers concerning enzyme–nanoparticle based bioelectronic devices, it is stated that the presence of nanoparticles on electrode surfaces per se enhances bioelectrocatalysis, although the reasons for that enhancement are often unclear. Here, we report detailed experimental evidence that neither an overpotential of bioelectrocatalysis, nor direct electron transfer and bioelectrocatalytic reaction rates for an adsorbed enzyme depend on the size of nanoparticles within the range of 20–80 nm, i.e. for nanoparticles that are considerably larger than the enzyme molecules.
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| 13. |
- Pankratov, Dmitry, et al.
(author)
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The influence of nanoparticles on enzymatic bioelectrocatalysis
- 2014
-
In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:72, s. 38164-38168
-
Journal article (peer-reviewed)abstract
- In nearly all papers concerning enzyme-nanoparticle based bio-electronic devices, it is stated that the presence of nanoparticles on electrode surfaces per se enhances bioelectrocatalysis, although the reasons for that enhancement are often unclear. Here, we report detailed experimental evidence that neither an overpotential of bioelectrocatalysis, nor direct electron transfer and bioelectrocatalytic reaction rates for an adsorbed enzyme depend on the size of nanoparticles within the range of 20-80 nm, i.e. for nanoparticles that are considerably larger than the enzyme molecules.
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| 14. |
- Schroeder, Viktor, et al.
(author)
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Dynamic Guiding of Motor-Driven Microtubules on Electrically Heated, Smart Polymer Tracks
- 2013
-
In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:7, s. 3434-3438
-
Journal article (peer-reviewed)abstract
- Biomolecular motor systems are attractive for future nanotechnological devices because they can replace nanofluidics by directed transport. However, the lack of methods to externally control motor-driven transport along complex paths limits their range of applications. Based on a thermo-responsive polymer, we developed a novel technique to guide microtubules propelled by kinesin-1 motors on a planar surface. Using electrically heated gold microstructures, the polymers were locally collapsed, creating dynamically switchable tracks that successfully guided microtubule movement.
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| 15. |
- Schwenke, Jörg, et al.
(author)
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Digital in-line holography on amplitude and phase objects prepared with electron beam lithography.
- 2012
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In: Journal of Microscopy. - : Wiley. - 0022-2720. ; 247:2, s. 196-201
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Journal article (peer-reviewed)abstract
- We report on the fabrication and characterization of amplitude and phase samples consisting of well defined Au or Al features formed on ultrathin silicon nitride membranes. The samples were manufactured using electron beam lithography, metallization and a lift-off technique, which allow precise lateral control and thickness of the metal features. The fabricated specimens were evaluated by conventional microscopy, atomic force microscopy and with the digital in-line holography set-up at the Lund Laser Centre. The latter uses high-order harmonic generation as a light source, and is capable of recovering both the shape and phase shifting properties of the samples. We report on the details of the sample production and on the imaging tests with the holography set-up.
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| 16. |
- Sun, Jie, 1977, et al.
(author)
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Gate-defined double quantum dot with integrated charge sensors realized in InGaAs/InP by incorporating a high- κ dielectric
- 2010
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 96:16
-
Journal article (peer-reviewed)abstract
- A gate-defined double quantum dot with two integrated quantum point contact charge sensors is realized in an InGaAs/InP heterostructure by employing a high-kappa HfO2 thin film as gate dielectric and a polymer bridge technique. Clear honeycomb patterns are observed in the measured charge stability diagram of the double quantum dot and charge sensing signals of the quantum point contacts. It is also found that the quantum point contact charge sensors can detect the charge states in the double quantum dot even in the condition that the direct transport signal is not visible.
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| 17. |
- Sun, Jie, et al.
(author)
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Memristive and Memcapacitive Characteristics of a Au/Ti-HfO2-InP/InGaAs Diode
- 2011
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In: IEEE Electron Device Letters. - 0741-3106. ; 32:2, s. 131-133
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Journal article (peer-reviewed)abstract
- This letter reports on room-temperature electrical measurements of a Au/Ti-HfO2-InP/InGaAs diode fabricated by atomic layer deposition and electron beam lithography. At forward bias voltages, the diode shows memristor characteristics, whereas at reverse bias voltages, the diode can be characterized as a memcapacitor. A parasitic accumulation layer of charges formed at the high-kappa oxide/InP interface is shown to be the cause for the phenomena. The operation of the diode as a rewritable memory cell is also demonstrated. The results highlight novel memristive and memcapacitive properties of high-kappa dielectrics on III-V semiconductors and their potential applications in nanoelectronics.
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| 18. |
- Suyatin, Dmitry, et al.
(author)
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Strong Schottky barrier reduction at Au-catalyst/GaAs-nanowire interfaces by electric dipole formation and Fermi-level unpinning
- 2014
-
In: Nature Communications. - London : Springer Science and Business Media LLC. - 2041-1723. ; 5
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Journal article (peer-reviewed)abstract
- Nanoscale contacts between metals and semiconductors are critical for further downscaling of electronic and optoelectronic devices. However, realizing nanocontacts poses significant challenges since conventional approaches to achieve ohmic contacts through Schottky barrier suppression are often inadequate. Here we report the realization and characterization of low n-type Schottky barriers (~0.35 eV) formed at epitaxial contacts between Au-In alloy catalytic particles and GaAs-nanowires. In comparison to previous studies, our detailed characterization, employing selective electrical contacts defined by high-precision electron beam lithography, reveals the barrier to occur directly and solely at the abrupt interface between the catalyst and nanowire. We attribute this lowest-to-date-reported Schottky barrier to a reduced density of pinning states (~1017 m−2) and the formation of an electric dipole layer at the epitaxial contacts. The insight into the physical mechanisms behind the observed low-energy Schottky barrier may guide future efforts to engineer abrupt nanoscale electrical contacts with tailored electrical properties.
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