| 1. |
- Chiragwandi, Zackary, 1968, et al.
(författare)
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Vortex rings in pure water under static external electric field
- 2005
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Ingår i: APPLIED PHYSICS LETTERS 87 (15): Art. No. 153109. - : AIP Publishing. ; 87(15):15, s. 1-3
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Tidskriftsartikel (refereegranskat)abstract
- The reproducible development of vortex rings in pure water under the action of a static external electric field is demonstrated. The phenomenon results from the electrochemical decomposition of water. Given the low conductivity of water in the absence of electrolyte, the field-driven buildup of hydroxide ions at the anode becomes essential to the proton release, which in turn is the result of the molecular O-2(g) evolution. Water recombination processes, which have protons flowing in a hydroxide background, as a key ingredient produce the phenomenon. (C) 2005 American Institute of Physics.
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| 2. |
- Da Silva, A. F., et al.
(författare)
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Linear optical response of Si1-xGex compounds
- 2005
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Ingår i: Quantum Sensing and Nanophotonic Devices II. - : SPIE - International Society for Optical Engineering. - 081945706X ; 5732:1, s. 556-564
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Konferensbidrag (refereegranskat)abstract
- Si1-xGex is a good candidate as a substitute material for Si in a low-power and high-speed semiconductor device technologies. Optical devices, such as heterojunction bipolar transistors, are already in industrial production. The samples are grown on Si(001) with both n-and p-type impurities and with different Ge concentrations. The linear optical response of Si 1-x Gex is investigated theoretically using a full-potential linearized augmented plane wave method with respect to composition x. The calculated real and imaginary parts of the dielectric function ε e(ω) = ε1(ω) + iε 2(ω) were found to be in good agreement with recent spectroscopic ellipsometry measurements performed by Bahng et al., J. Phys.: Condens. Matter 13, 777 (2001). We also perform absorption measurements for different type of samples showing the variation of energy gaps as a function of Ge concentrations.
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| 3. |
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| 4. |
- Klason, Peter, 1977, et al.
(författare)
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Fabrication and characterization of p-Si/n-ZnO heterostructured junctions
- 2008
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Ingår i: Microelectronics Journal.
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Tidskriftsartikel (refereegranskat)abstract
- In this paper ZnO nanorods and nanodots (with and without a SiO2 buffer layer) were grown on p-Si, forming p–n heterojunctions. The nanorod devices showed no visible electroluminescence (EL) emission but showed rectifying behavior. Covering around 60% of the length of the nanorods with PMMA produced an ideality factor of 3.91±0.11 together with a reverse saturation current of View the MathML source. Up to two orders of magnitude rectification was observed for the current at bias -3 and 3 V. The nanodot devices showed EL emission under forward bias conditions. It seems that the buffer layer increased both the stability and efficiency of the devices, since the buffer layer device could operate at larger applied voltage and showed EL emission under reverse bias.
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| 5. |
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| 6. |
- Persson, Clas Marcus, et al.
(författare)
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Electronic band-edge structure, effective masses, and optical absorption of Si1-xGex using an extended FPLAPW/VCA/LDA+U computational method
- 2006
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Ingår i: Brazilian journal of physics. - : Sociedade Brasileira de Fisica. - 0103-9733 .- 1678-4448. ; 36:2 A, s. 447-450
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Tidskriftsartikel (refereegranskat)abstract
- Electronic band-edge structure and optical properties of Si 1-xGex are investigated theoretically emloying a full-potential linearized augmented plane wave (FPLAPW) method. The exchange-correlation potential in the local density approximation (LDA) is corrected by an on-site Coulomb potential (i.e., within the LDA.+USIC approach) acting asymmetrically on the atomic-like orbitals in the muffin-tin spheres. The electronic structure of the Si1-xGex is calculated self-consistently, assuming a Td symmetrized Hamiltonian and a linear behavior of the valence-band eigenfunctions for Si, SiGe, and Ge with respect to Ge composition x, assuming randomly alloyed crystal structure, i.e., a "virtual-crystal like" approximation (VGA). We show that this approach yields accurate band-gap energies, effective masses, dielectric function, and optical properties of Si1-xGex. We perform absorption measurements showing the band-gap energy for x < 0.25.
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| 7. |
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| 8. |
- Soliveres, S., et al.
(författare)
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Excess low frequency noise in single-wall carbon nanotube
- 2006
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Ingår i: Fluctuation and Noise Letters. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 0219-4775 .- 1793-6780. ; 6:1, s. L45-L55
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Tidskriftsartikel (refereegranskat)abstract
- Low frequency noise measurements have been performed on a single-wall carbon nanotube connected by Ti/Au electrodes. It has been found that the 1/f noise decreases when the measurements are undertaken under vacuum and when the nanotube is partially degassed, showing a correlation between the fluctuation inducing the 1/f noise and the presence of gases. We show that the 1/f noise sources are located at the metal/nanotube contacts. When the device is annealed under vacuum at 450K, some Lorentzian shapes are observable and can be related to nanotube defects or to strongly bound molecules. © World Scientific Publishing Company.
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| 9. |
- Soliveres, S., et al.
(författare)
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Low frequency noise in contacted single-wall carbon nanotube
- 2005
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Ingår i: AIP Conference Proceedings. - 0094-243X. ; 780, s. 462-465
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Konferensbidrag (refereegranskat)abstract
- Since their discovery, carbon nanotubes present many interesting electrical properties and can be candidates for future shrinking devices. Electrode realization on nanotubes remains a challenge. The deposited contacts must present interesting electrical parameters: low contact resistance, low series resistance, low parasitic capacity and low excess noise. The understanding of conduction phenomena induced into or near the metal/nanotube contact is necessary to improve the device. In this paper we present characterization of a Au-Ti deposited contact on a single-wall carbon nanotube. Steady-state current-voltage measurements, impedance and noise measurements lead to the frequency device characteristic. From this study a low frequency noise electrical model is presented. Using this model and the low frequency noise measurements, we show that the measured thermal noise has its origin in the electrode/nanotube contacts.
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| 10. |
- Willander, Magnus, 1948, et al.
(författare)
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Fundamentals and properties of zinc oxide nanostructures: optical and sensing applications
- 2008
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Ingår i: Superlattices and Microstructures. - : Elsevier BV. - 0749-6036 .- 1096-3677. ; 43:4, s. 352-61
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we will give an overview of the status of catalytic growth and of low-temperature chemical growth of ZnO nanostructures performed in our laboratory. Particularly results employing different substrates will be discussed. The second part deals with structural and optical properties of ZnO nanorods. The results from high resolution transmission electron microscope (HRTEM), scanning electron microscope (SEM), photoluminescence (PL), Cathodoluminescence (CL), and Electroluminescence (EL), on single nanowires will be shown. Our results on surface morphology, bulk and the position of the catalyst as well as the optical properties including UV emission, lasing and white emission will all be presented and discussed. In the third part experimental results from electroluminescence of ZnO nanorods on different substrates in the UV in addition to excellent white light emission obtained from samples grown at low temperature are to be given and discussed. Finally the sensing of molecules in water by ZnO nanorods will be discussed from a theoretical point of view. Also fundamental properties of polaritons and excitons in ZnO nanostructures are to be highlighted.
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