| 1. |
- Ali, Hasan, 1985-, et al.
(författare)
-
An electron energy loss spectrometer based streak camera for time resolved TEM measurements
- 2017
-
Ingår i: Ultramicroscopy. - : Elsevier BV. - 0304-3991 .- 1879-2723. ; 176, s. 5-10
-
Tidskriftsartikel (refereegranskat)abstract
- We propose an experimental setup based on a streak camera approach inside an energy filter to measure time resolved properties of materials in the transmission electron microscope (TEM). In order to put in place the streak camera, a beam sweeper was built inside an energy filter. After exciting the TEM sample, the beam is swept across the CCD camera of the filter. We describe different parts of the setup at the example of a magnetic measurement. This setup is capable to acquire time resolved diffraction patterns, electron energy loss spectra (EELS) and images with total streaking times in the range between 100 ns and 10 μs.
|
|
| 2. |
- Calard, Francois, et al.
(författare)
-
Designing sterically demanding thiolate coated AuNPs for electrical characterization of BPDT in a NP-molecule-nanoelectrode platform
- 2017
-
Ingår i: Molecular Systems Design & Engineering. - : ROYAL SOC CHEMISTRY. - 2058-9689. ; 2:2, s. 133-139
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular electronics with single or few molecules requires a stable metal-molecule nanojunction platform. Herein, we report the design and synthesis of gold nanoparticles coated with sterically demanding thiol ligands that are essential to fabricate a versatile and stable nanoelectrode-molecule-nanoparticle platform suitable for electrical characterization of small organic molecules. By combining.-tetraphenylmethane ether functionalized alkyl thioacetate and alkyl thiols, we prepared highly stable gold nanoparticles in a one-phase reaction providing simple and efficient purification. This robust preparation gives highly pure nanoparticles in very high yields (up to 90%) with long-time shelf stability. The synthesis in this work has superior reproducibility compared to previous synthesis processes that are currently being used for such molecular electronics platforms. Electron microscopy confirms the formation of uniform and small nanoparticles in the range of 5 to 7 nm. These nanoparticles with different ligand surface coverages were placed in a 20 nm nanoelectrode setup using dielectrophoretic forces. This setup was utilized to characterize the conductivity of the molecular wire 4,4'-biphenyldithiol introduced via ligand placeexchange under ambient conditions.
|
|
| 3. |
- Faraz, S. M., et al.
(författare)
-
Effect of annealing temperature on the interface state density of n-ZnO nanorod/p-Si heterojunction diodes
- 2021
-
Ingår i: Open Physics. - : De Gruyter Open Ltd. - 2391-5471. ; 19:1, s. 467-476
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of post-growth annealing treatment of zinc oxide (ZnO) nanorods on the electrical properties of their heterojunction diodes (HJDs) is investigated. ZnO nanorods are synthesized by the low-temperature aqueous solution growth technique and annealed at temperatures of 400 and 600°C. The as-grown and annealed nanorods are studied by scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. Electrical characterization of the ZnO/Si heterojunction diode is done by current–voltage (I–V) and capacitance–voltage (C–V) measurements at room temperature. The barrier height (ϕB), ideality factor (n), doping concentration and density of interface states (NSS) are extracted. All HJDs exhibited a nonlinear behavior with rectification factors of 23, 1,596 and 309 at ±5 V for the as-grown, 400 and 600°C-annealed nanorod HJDs, respectively. Barrier heights of 0.81 and 0.63 V are obtained for HJDs of 400 and 600°C-annealed nanorods, respectively. The energy distribution of the interface state density has been investigated and found to be in the range 0.70 × 1010 to 1.05 × 1012 eV/cm2 below the conduction band from EC = 0.03 to EC = 0.58 eV. The highest density of interface states is observed in HJDs of 600°C-annealed nanorods. Overall improved behavior is observed for the heterojunctions diodes of 400°C-annealed ZnO nanorods. © 2021 Sadia Muniza Faraz et al.
|
|
| 4. |
- Ilyas, Sameen, et al.
(författare)
-
Tuning of electrical conduction properties of natural fibers and TiO 2 based flexible paper composite sheets by electrodeposition of metallic nanolayers
- 2021
-
Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842. ; 47:20, s. 29435-29442
-
Tidskriftsartikel (refereegranskat)abstract
- In an era of modern smart technology, flexible electrodes are of great interest for different energy conversion as well as energy storage applications like solar cells, all solid-state batteries, and supercapacitors. Flexible metal oxide-based paper electrodes are advantageous in comparison to conventional electrodes due to their economical synthesis, biocompatibility, and environment-friendly characteristics. However, the electrical conductivity of paper electrodes is limited because of the insulating nature of natural fibers employed as a binder for the flexible matrix of metal oxides. The current study is an attempt to tune the electrical properties of lignocelluloses (natural fibers) and titanium dioxide (TiO2) based paper electrodes by facile electrodeposition technique. The crystalline parts (e.g., TiO2, Ag, and Au) of the prepared composite sheets were characterized by XRD analysis while the surface morphology was studied by SEM. FTIR was used to characterize the organic matter in LC fibers by identifying various molecular stretching and vibrational modes of C, H, and O-containing molecules. Electric permittivity was measured as a function of electric field frequency at room temperature which revealed the value of 23. 5 (at 1 kHz) for the sample LC/TiO2/Ag 9000s indicating the best charge storing capability of the sample. Impedance analysis was employed to identify various charge carrier mechanisms active in the sheets. It was found through impedance analysis that there is an active diffusion-controlled impedance mechanism of Au-coated samples causing an increased conductivity via the ionic diffusion. This diffusion-controlled conduction was modeled by the Warburg element. The enhanced conductivity due to ionic diffusion makes these samples more useful as electrodes. Cyclic voltammetry (CV) measurements of the electrodeposited samples established the increase in conductive properties and efficient kinetics of LC/TiO2 paper sheets. The current study suggests that Ag and Au-coated paper electrodes can be potential candidates for energy conversion and storage applications.
|
|
| 5. |
- Jafri, S. Hassan M., et al.
(författare)
-
Assessment of a nanoparticle bridge platform for molecular electronics measurements
- 2010
-
Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 21:43, s. 435204-
-
Tidskriftsartikel (refereegranskat)abstract
- A combination of electron beam lithography, photolithography and focused ion beam milling was used to create a nanogap platform, which was bridged by gold nanoparticles in order to make electrical measurements and assess the platform under ambient conditions. Non-functionalized electrodes were tested to determine the intrinsic response of the platform and it was found that creating devices in ambient conditions requires careful cleaning and awareness of the contributions contaminants may make to measurements. The platform was then used to make measurements on octanethiol (OT) and biphenyldithiol (BPDT) molecules by functionalizing the nanoelectrodes with the molecules prior to bridging the nanogap with nanoparticles. Measurements on OT show that it is possible to make measurements on relatively small numbers of molecules, but that a large variation in response can be expected when one of the metal-molecule junctions is physisorbed, which was partially explained by attachment of OT molecules to different sites on the surface of the Au electrode using a density functional theory calculation. On the other hand, when dealing with BPDT, high yields for device creation are very difficult to achieve under ambient conditions. Significant hysteresis in the I-V curves of BPDT was also observed, which was attributed primarily to voltage induced changes at the interface between the molecule and the metal.
|
|
| 6. |
|
|
| 7. |
- Li, Hu, et al.
(författare)
-
Fabrication of reproducible sub-5 nm nanogaps by a focused ion beam and observation of Fowler-Nordheim tunneling
- 2015
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 107:10
-
Tidskriftsartikel (refereegranskat)abstract
- Creating a stable high resistance sub-5 nm nanogap in between conductive electrodes is one of the major challenges in the device fabrication of nano-objects. Gap-sizes of 20 nm and above can be fabricated reproducibly by the precise focusing of the ion beam and careful milling of the metallic lines. Here, by tuning ion dosages starting from 4.6 x 10(10) ions/cm and above, reproducible nanogaps with sub-5 nm sizes are milled with focused ion beam. The resistance as a function of gap dimension shows an exponential behavior, and Fowler-Nordheim tunneling effect was observed in nanoelectrodes with sub-5 nm nanogaps. The application of Simmon's model to the milled nanogaps and the electrical analysis indicates that the minimum nanogap size approaches to 2.3 nm.
|
|
| 8. |
- Promnimit, S., et al.
(författare)
-
Conduction Properties of Layer-by-Layer Self-Assembled Multilayer Nanoparticulate Structures
- 2008
-
Ingår i: Journal of Nanoelectronics and Optoelectronics. - : American Scientific Publishers. - 1555-130X .- 1555-1318. ; 3:2, s. 184-189
-
Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles based multilayer fabricated using layer-by-layer (LbL) self assembly process mediated through polyelectrolytes is reported as an interesting alternative for the fabrication of electronic devices. The effect of deposition cycle on the current-voltage characteristics of thin multilayer devices composed of alternating layers of chitosan-capped zinc sulphide nanoparticles (0 = 35 nm) and gold nanoparticles (0 = 20 nm), deposited onto a conducting indium tin oxide (ITO) coated glass substrate is reported. The current voltage (I-V) characteristics of multilayer devices with an increasing number of layers show an initial current blockade until an onset voltage value, which increases linearly upon the addition of the number of the layers stacked in the device. A conductive behavior of the device could be observed after exceeding the onset voltage. The conduction onset voltage is enhanced from similar to 0.14 V to similar to 5.6 V by increasing deposition cycles, from n = 5 to 100. Symmetric current-voltage characteristics can be observed both under forward and reverse bias conditions.
|
|
| 9. |
|
|
| 10. |
|
|
