| 1. |
- Abdel, Naseem, et al.
(författare)
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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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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499. ; 60:2, s. 1182-1188
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Journal of Instrumentation. - 1748-0221. ; 9
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Fabrication of bottle-shaped nanochannels in fused silica using a self-closing effect
- 2012
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 97, s. 173-176
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Tidskriftsartikel (refereegranskat)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.
(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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| 6. |
- 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
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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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| 7. |
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| 8. |
- 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
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 13:10, s. 4654-4658
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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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| 9. |
- Meng, Fantao, et al.
(författare)
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Efficient methods of nanoimprint stamp cleaning based on imprint self-cleaning effect.
- 2011
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 22:18
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 1873-5568 .- 0167-9317. ; 88:10, s. 3108-3112
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Tidskriftsartikel (refereegranskat)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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