| 1. |
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| 2. |
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| 3. |
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| 4. |
- Semchuk, O. Yu., et al.
(författare)
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Features of coherent laser beams interaction with condensed matter
- 2004
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Ingår i: Appl. Surf. Sci.. - : Elsevier BV. - 0169-4332. ; 234:1-4, s. 415-421
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Tidskriftsartikel (refereegranskat)abstract
- Some mechanisms of formation of laser-induced periodic surface and bulk structures in condensed matter are considered. Their influence on optical properties of semiconductors is investigated. It is shown that under action of coherent laser beams (CLBs) a grating of the refraction index arises in semiconductors. The models featuring this effect are offered. The relevant theoretical calculations confirming occurrence the new phenomenon — appearance of a grating of the refractive index in semiconductors in a field of CLBs — were carried out. It is shown that in ferromagnetic semiconductors (FMSC) with a laser-induced grating of the magnon temperature one probably deals with occurrence of the nonlinearity of the refraction index caused by the nonlinearity of FMSC magnetic susceptibility and one should observe oscillations of a refraction index, which will result in occurrence of complementary darkened areas.
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| 5. |
- Semchuk, O. Yu., et al.
(författare)
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Features of transport phenomenas in magnetic semiconductors with laser-induced periodic nanostructures
- 2007
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936 .- 0928-4931 .- 1873-0191. ; 27:5-8, s. 1360-1363
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of formation of the laser-induced periodic surface and bulk nanostructures in magnetic semiconductors are considered. Their influence on transport phenomena in ferromagnetic semiconductors (FMSC) is investigated. It is shown that under action of laser beams (LB) a laser-induced periodic nanostructures — gratings of the electron and magnon temperatures, electron concentration and electric fields arises in FMSC. It is determined, that the illuminating of an external surface of the FMSC by several LB results in an emerging new effect — appearance of a dropping site on the voltage-current characteristic (VCC) of the FMSC with the static laser-induced periodic nanostructures. This effect can only be observed for the carrier concentration n ≥ 1018 cm−3, since for smaller concentration the contribution of an additional current caused by the presence of the laser-induced periodic nanostructures will be insignificant.
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| 6. |
- Semchuk, O. Yu, et al.
(författare)
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Laser ablation lithography on thermoelectric semconductor
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:13, s. 4759-4762
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found.
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| 7. |
- Svensson, Bengt Gunnar, et al.
(författare)
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Hydrothermally Grown Single-Crystalline Zinc Oxide; Characterization and Modification
- 2007
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Ingår i: MRS Proceedings Volume 1035 / 2007. - Warrendale, PA, USA : Materials Research Society.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An overview of our recent results on characterization and modification of high-resistivity n-type bulk zinc oxide samples, grown by hydrothermal techniques, is given. Three specific topics are addressed; (i) the role of lithium (Li) as an electrically compensating impurity, (ii) extrinsic n-type doping by hydrogen implantation, and (iii) influence of annealing conditions on deep band emission. In (i), furnace annealing of as-grown samples at temperatures above ∼800 °C is shown to cause out-diffusion of residual Li impurities and concurrently, the resistivity decreases. After annealing at 1400 °C, a resistivity close to 10−1 Ωcm is obtained and the Li content is reduced from above 1017 cm−3 to the mid 1015 cm−3 range, providing evidence for the crucial role of Li as an electrically compensating impurity. For ion-implanted samples, vacancy clusters evolve during post-implant flash lamp annealing (20 ms duration) and these clusters appear to trap and deactivate Li with a resulting improvement of the n-type conductivity. However, these clusters have a limited stability and start to dissociate already after 1h at 900 °C, accompanied by a decrease in the conductivity. For topic (ii), n-type doping by hydrogen implantation is shown to enhance the conductivity by about 5 orders of magnitude already in the as-implanted state. Despite substantial loss of hydrogen, the conductivity remains stable, or even increases, after annealing up to ≥600 °C, and necessary conditions for doping by hydrogen are discussed. In (iii), the origin of the commonly observed deep band emission from monocrystalline zinc oxide is investigated using a concept of annealing as-grown samples in different atmospheres. A strong influence by the atmosphere and temperature is observed and the results can be interpreted in terms of dominant effects on the emission by vacancy-related defects.
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| 8. |
- Wang, JH, et al.
(författare)
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Microstructure of Ni-based self-fluxing alloy coating (Part I)
- 2005
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Ingår i: Journal of Iron and Steel Research International. - Amsterdam : Elsevier Science B.V. - 1006-706X .- 2210-3988. ; 12:1, s. 50-53
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure of a Ni-based self-fluxing alloy coating produced by an oxygen-acetylene flame spraying Ni-16. 5Cr-3. 3B-4. 7Si-4. 4Fe-0.8C system alloy powder onto a common steel substrate was investigated by microanalysis methods. The phases in the coating were observed by SEM and determined by XEDS X-Ray energy spectrum and X Ray diffraction patterns. Meanwhile, some molecular formulas were calculated.
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| 9. |
- Willander, Magnus, 1948, et al.
(författare)
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High-Temperature Electronic Materials: Silicon Carbide and Diamond
- 2007
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Ingår i: Springer Handbooks. - Boston, MA : Springer US. ; , s. 537-563
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The physical and chemical properties of wide-band-gap semiconductors make these materials an ideal wide bandgapsemiconductor choice for device fabrication for applications in many different areas, e.g. light emitters, high-temperature and high-power electronics, high-power microwave devices, micro-electromechanical system (MEM) technology, and substrates for semiconductor preparation. These semiconductors have micro-electromechanical system (MEMS) been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high-quality devices. In this material quality chapter, we review the wide-band-gap semiconductors, silicon carbide and diamond. Silicon carbide electronics is advancing from the research stage to commercial production. The commercial availability of single-crystal SiC substrates during the early 1990s gave rise to intense activity in the development of silicon carbide devices. The commercialization started with the release of blue light-emitting diode (LED). The recent release of high-power Schottky diodes was a further demonstration of the progress made towards defect-free SiC substrates. Diamond has superior physical and chemical properties. Silicon-carbide- and diamond-based diamondsilicon carbide (SiC) electronics are at different stages of development. The preparation of high-quality single-crystal substrates of wafer size has allowed recent significant progress in the fabrication of several types of devices, and the development has reached many important milestones. However, high-temperature studies are still scarce, and diamond-based electronics is still in its infancy.
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| 10. |
- Willander, Magnus, 1948-, et al.
(författare)
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Silicon carbide and diamond for high temperature device applications
- 2006
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Ingår i: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- The physical and chemical properties of wide bandgap semiconductors silicon carbide and diamond make these materials an ideal choice for device fabrication for applications in many different areas, e.g. light emitters, high temperature and high power electronics, high power microwave devices, micro-electromechanical system (MEMS) technology, and substrates. These semiconductors have been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high quality devices. Silicon carbide and diamond based electronics are at different stages of their development. An overview of the status of silicon carbide's and diamond's application for high temperature electronics is presented. Silicon carbide electronics is advancing from the research stage to commercial production. The most suitable and established SiC polytype for high temperature power electronics is the hexagonal 4H polytype. The main advantages related to material properties are: its wide bandgap, high electric field strength and high thermal conductivity. Almost all different types of electronic devices have been successfully fabricated and characterized. The most promising devices for high temperature applications are pn-diodes, junction field effect transistors and thyristors. MOSFET is another important candidate, but is still under development due to some hidden problems causing low channel mobility. For microwave applications, 4H-SiC is competing with Si and GaAs for frequency below 10 GHz and for systems requiring cooling like power amplifiers. The unavailability of high quality defect and dislocation free SiC substrates has been slowing down the pace of transition from research and development to production of SiC devices, but recently new method for growth of ultrahigh quality SiC, which could promote the development of high power devices, was reported. Diamond is the superior material for high power and high temperature electronics. Fabrication of diamond electronic devices has reached important results, but high temperature data are still scarce. PN-junctions have been formed and investigated up to 400 °C. Schottky diodes operating up to 1000 °C have been fabricated. BJTs have been fabricated functioning in the dc mode up to 200 °C. The largest advance, concerning development of devices for RF application, has been done in fabrication of different types of FETs. For FETs with gate length 0.2 μm frequencies fT = 24.6 GHz, fmax(MAG) = 63 GHz and fmax(U) = 80 GHz were reported. Further, capacitors and switches, working up to 450 °C and 650 °C, respectively, have also been fabricated. Low resistant thermostable resistors have been investigated up to 800 °C. Temperature dependence of field emission from diamond films has been measured up to 950 °C. However, the diamond based electronics is still regarded to be in its infancy. The prerequisite for a successful application of diamond for the fabrication of electronic devices is availability of wafer diamond, i.e. large area, high quality, inexpensive, diamond single crystal substrates. A step forward in this direction has been made recently. Diamond films grown on multilayer substrate Ir/YSZ/Si(001) having qualities close those of homoepitaxial diamond have been reported recently. © Springer Science + Business Media, Inc. 2006.
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| 11. |
- Zhao, Qingxiang, 1962, et al.
(författare)
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Nitrogen incorporation in GaNas layers grown by molecular beam epitaxy
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:3, s. 31907-1-31907-3
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Tidskriftsartikel (refereegranskat)abstract
- GaNAs/GaAs quantum wells with high N concentrations, grown by molecular beam epitaxy, have been investigated by secondary-ion mass spectrometry (SIMS), high resolution x-ray diffraction (XRD), and photoluminescence (PL) measurements. The substitutional N concentration in an 18 nm thick strained GaNAs layer varies from 1.4% to 5.9% when the growth rate is reduced from 1 to 0.2 μm/h. By further reducing the growth rate, more N can be incorporated but relaxation occurs. Both the total N concentration, deduced from SIMS measurements, and the substitutional N concentration, deduced from XRD measurements, increase with reduced growth rate. By comparing the SIMS and XRD results, we found that a large amount of N was not in substitutional position when the substitutional N concentration is high (≫4%). The experimental results also show that there is no detectable change of total and substitutional N concentrations, within the instrument resolutions, after rapid thermal annealing at 700 °C for 30 s. However, PL measurements show a strong blueshift of the emission wavelength after annealing and the PL intensity increases by more than one order of magnitude.
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| 12. |
- Adam, Rania Elhadi, 1978-, et al.
(författare)
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Graphene-based plasmonic nanocomposites for highly enhanced solar-driven photocatalytic activities
- 2019
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Ingår i: RSC Advances. - Cambridge : Royal Meteorological Society. - 2046-2069. ; 9:52, s. 30585-30598
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Tidskriftsartikel (refereegranskat)abstract
- High-efficiency photocatalysts are crucial for the removal of organic pollutants and environmental sustainability. In the present work, we report on a new low-temperature hydrothermal chemical method, assisted by ultrasonication, to synthesize disruptive plasmonic ZnO/graphene/Ag/AgI nanocomposites for solar-driven photocatalysis. The plasmonic nanocomposites were investigated by a wide range of characterization techniques, confirming successful formation of photocatalysts with excellent degradation efficiency. Using Congo red as a model dye molecule, our experimental results demonstrated a photocatalytic reactivity exceeding 90% efficiency after one hour simulated solar irradiation. The significantly enhanced degradation efficiency is attributed to improved electronic properties of the nanocomposites by hybridization of the graphene and to the addition of Ag/AgI which generates a strong surface plasmon resonance effect in the metallic silver further improving the photocatalytic activity and stability under solar irradiation. Scavenger experiments suggest that superoxide and hydroxyl radicals are responsible for the photodegradation of Congo red. Our findings are important for the fundamental understanding of the photocatalytic mechanism of ZnO/graphene/Ag/AgI nanocomposites and can lead to further development of novel efficient photocatalyst materials.
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| 13. |
- Adam, Rania Elhadi, 1978-
(författare)
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Synthesis and Characterization of Some Nanostructured Materials for Visible Light-driven Photo Processes
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nanostructured materials for visible light driven photo-processes such as photodegradation of organic pollutants and photoelectrochemical (PEC) water oxidation for hydrogen production are very attractive because of the positive impact on the environment. Metal oxides-based nanostructures are widely used in these photoprocesses due to their unique properties. But single nanostructured metal oxide material might suffer from low efficiency and instability in aqueous solutions under visible light. These facts make it important to have an efficient and reliable nanocomposite for the photo-processes. The combination of different nanomaterials to form a composite configuration can produce a material with new properties. The new properties which are due to the synergetic effect, are a combination of the properties of all the counterparts of the nanocomposite. Zinc oxides (ZnO) have unique optical and electrical properties which grant it to be used in optoelectronics, sensors, solar cells, nanogenerators, and photocatalysis activities. Although ZnO absorbs visible light from the sun due to the deep level band, it mainly absorbs ultraviolet wavelengths which constitute a small portion of the whole solar spectrum range. Also, ZnO has a problem with the high recombination rate of the photogenerated electrons. These problems might reduce its applicability to the photo-process. Therefore, our aim is to develop and investigate different nanocomposites materials based on the ZnO nanostructures for the enhancement of photocatalysis processes using the visible solar light as a green source of energy. Two photo-processes were applied to examine the developed nanocomposites through photocatalysis: (1) the photodegradation of organic dyes, (2) PEC water splitting. In the first photo-process, we used the ZnO nanoparticles (NPs), Magnesium (Mg)-doped ZnO NPs, and plasmonic ZnO/graphene-based nanocomposite for the decomposition of some organic dyes that have been used in industries. For the second photo-process, ZnO photoelectrode composite with different silver-based semiconductors to enhance the performance of the ZnO photoelectrode was used for PEC reaction analysis to perform water splitting. The characterization and photocatalysis experiment results showed remarkable enhancement in the photocatalysis efficiency of the synthesized nanocomposites. The observed improved properties of the ZnO are due to the synergetic effects are caused by the addition of the other nanomaterials. Hence, the present thesis attends to the synthesis and characterization of some nanostructured materials composite with ZnO that are promising candidates for visible light-driven photo-processes.
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| 14. |
- Adam, Rania Elhadi, 1978-, et al.
(författare)
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Synthesis of Mg-doped ZnO NPs via a chemical low-temperature method and investigation of the efficient photocatalytic activity for the degradation of dyes under solar light
- 2020
-
Ingår i: Solid State Sciences. - : Elsevier. - 1293-2558 .- 1873-3085. ; 99
-
Tidskriftsartikel (refereegranskat)abstract
- Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 °C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2θ angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.
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| 15. |
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| 16. |
- Al-Hilli, Safaa, 1965, et al.
(författare)
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Zinc oxide nanorod for intracellular pH sensing
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:17, s. 073119-1-073119-3
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Tidskriftsartikel (refereegranskat)abstract
- pH determination is a prerequisite for many biochemical and biological processes. The authors have used two methods, namely, the electrochemical potential method and the site binding method to study the sensitivity of zinc oxide (ZnO) nanorods for the use as intracellular pH sensing device. The dimensions of these nanorods were varied with radii between 50–300 nm and lengths between 2 and 10 μm. The ZnO nanorods showed a high sensitivity ≈ 59 mV per decade at room temperature for a pH range (1–14), assuming that the solution is water. This is expected due to the polar and nonpolar surfaces of the ZnO nanorods.
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| 17. |
- Al-Hilli, Safaa, 1965, et al.
(författare)
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Zinc oxide nanorods grown on two-dimensional macroporous periodic structures and plane Si as a pH sensor
- 2008
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 103:1, s. 014302-014309
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Tidskriftsartikel (refereegranskat)abstract
- pH determination is a strong prerequisite for many biochemical and biological processes. We used two methods, namely, the electrochemical potential method (experimental) and site binding method (theoretical), to study the sensitivity of zinc oxide (ZnO) nanorods grown on two-dimensional macroporous periodic structures (2DMPPS) (p-and n-type) and plane n-type Si substrates for use as an intracellular pH sensing device. The dimension of these nanorods varied in radius between 50 and 300 nm and lengths of 1–10 μm. We found that the sensitivity of ZnO nanorods increases with reductions in size, from 35 mV/pH for D = 300 nm and L = 10 μm, to 58 mV/pH for D = 50 nm and L = 1 μm, using the site binding model. The experimental electrochemical potential difference for the ZnO nanorods working electrode versus Ag/AgCl reference electrode showed a high sensitivity range for ZnO nanorods grown on 2DMPPS n-Si substrate as compared to plane n-Si at room temperature for pH ranging from 4 to 12 in buffer and NaCl solutions
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| 18. |
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| 19. |
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| 20. |
- Alnoor, Hatim, 1979-
(författare)
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Toward the Optimization of Low-temperature Solution-based Synthesis of ZnO Nanostructures for Device Applications
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One-dimensional (1D) nanostructures (NSs) of Zinc Oxide (ZnO) such as nanorods (NRs) have recently attracted considerable research attention due to their potential for the development of optoelectronic devices such as ultraviolet (UV) photodetectors and light-emitting diodes (LEDs). The potential of ZnO NRs in all these applications, however, would require synthesis of high crystal quality ZnO NRs with precise control over the optical and electronic properties. It is known that the optical and electronic properties of ZnO NRs are mostly influenced by the presence of native (intrinsic) and impurities (extrinsic) defects. Therefore, understanding the nature of these intrinsic and extrinsic defects and their spatial distribution is critical for optimizing the optical and electronic properties of ZnO NRs. However, identifying the origin of such defects is a complicated matter, especially for NSs, where the information on anisotropy is usually lost due to the lack of coherent orientation.Thus, the aim of this thesis is towards the optimization of the lowtemperature solution-based synthesis of ZnO NRs for device applications. In this connection, we first started with investigating the effect of the precursor solution stirring durations on the deep level defects concentration and their spatial distribution along the ZnO NRs. Then, by choosing the optimal stirring time, we studied the influence of ZnO seeding layer precursor’s types, and its molar ratios on the density of interface defects. The findings of these investigations were used to demonstrate ZnO NRs-based heterojunction LEDs. The ability to tune the point defects along the NRs enabled us further to incorporate cobalt (Co) ions into the ZnO NRs crystal lattice, where these ions could occupy the vacancies or interstitial defects through substitutional or interstitial doping. Following this, high crystal quality vertically welloriented ZnO NRs have been demonstrated by incorporating a small amount of Co into the ZnO crystal lattice. Finally, the influence of Co ions incorporation on the reduction of core-defects (CDs) in ZnO NRs was systematically examined using electron paramagnetic resonance (EPR).
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| 21. |
- Alshgari, Razan A., et al.
(författare)
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Manipulation of CuO morphology for efficient potentiometric detection of urea via slow nucleation/growth kinetics exerted by mixed solvents
- 2022
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Ingår i: Journal of materials science. Materials in electronics. - : SPRINGER. - 0957-4522 .- 1573-482X. ; 33, s. 25250-25262
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Tidskriftsartikel (refereegranskat)abstract
- Controlling the reaction kinetics during the nucleation/growth of cupric oxide (CuO) nanostructures is very critical in order to achieve a specific and well-defined morphology. For this purpose, we have slowed down the reaction speed using a mixed solvent concept and successfully obtained a chain-like morphology of CuO nanostructures using hydrothermal method. The CuO chain-like morphology was synthesized using a 1:1 (v/v) ratio of ethylene glycol and water. The morphology and crystalline features of CuO were studied by scanning electron microscopy (SEM) and powder X-ray diffraction techniques. The high resolution transmission electron microscopy revealed 5 nm crystallite size for the CuO material prepared in the mixed solvents. The obtained results have shown that the prepared CuO chains had a monocline phase, containing only Cu and O as main elements as confirmed by energy dispersive spectroscopy. This unique morphology obtained from mixed solvent process has provided a better surface for the loading of urease enzyme, thus it enabled the development of sensitive and selective urea biosensor in phosphate buffer solution of pH 7.4. The physical adsorption method was used to immobilize urease enzyme onto the nano surface of CuO. The fabricated biosensor based on urease/CuO chains has shown a dynamic linear range from 0.0005 to15 mM with a low limit of detection 0.0001 mM. Additionally, a fast response time aroudn1s, h high selectivity, stability, repeatability, storage time, and reproducibility were observed. The effect of pH and temperature on the potentiometric signal of the developed biosensor was also examined. Importantly, the practical aspects of the fabricated urea biosensor were probed and the obtained percent recovery results revealed an outstanding performance. The strategy of using mixed solvent with equal volume ratio would be useful for the preparation of other metal oxides with improved catalytic properties for a wide range of clinical, biomedical and other related applications.
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| 22. |
- Bellomo, Nicola, 1943, et al.
(författare)
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The generalized-kinetics-based equilibrium distribution function for composite particles
- 2003
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Ingår i: Comptes Rendus - Mecanique. - : Elsevier Science B.V., Amsterdam.. - 1631-0721 .- 1873-7234. ; 331:7, s. 461-467
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Tidskriftsartikel (refereegranskat)abstract
- This work is devoted to the equilibrium distribution function for a fluid of mutually non-interacting identical composite point particles in three-dimensional physical space. The distribution function is derived within the generalized-kinetics (GK) vision from the proposed probabilistic model based on quantum-mechanical bosons and fermions. The first GK advantage is that the derivation does not involve any assumption on the interpolation between bosons and fermions whereas the resulting function provides this interpolation. The second GK advantage is that composons, the particles described with the GK-based distribution function, are considerably less schematic and more consistent physically than quons. Composons correspond to a specific case of Isakov's general q-commutation relation involving an infinite number of the q-coefficients. Connection of the composon concept to previous results in the literature is pointed out. A few directions for future research on the topic are formulated. The results of the work can be used in the composite-particle fluid problems where the Maxwell–Boltzmann description is not valid, for instance, in dense populations of not too massive point-like particles of a complex, composite nature at not too high temperatures. FRENCH: Ce travail s'intéresse à la fonction de distribution d'équilibre pour un fluide mutuellement non agissant, composé de particules points dans un espace de dimension trois. La fonction de distribution provient, d'un point de vue de CG, d'un modèle probabiliste issu de la mécanique quantique des fermions et des bosons. Le premier avantage de CG est que la dérivation ne nécessite aucune hypothèse sur l'interpolation entre les bosons et les fermions alors que la fonction résultante fournit cette interpolation. Le second est que les composons, les particules décrites par ce procédé sont considérablement moins schématiques et plus consistantes, physiquement, que les quons. Les composons correspondent à un cas particulier de la relation générale de q-commutation d'Isakov, pour un nombre infini de q-coefficients. Les résultats antérieurs liés au concept de composon sont signalés et quelques directions de recherches futures sont proposées. Les résultats de ce travail peuvent servir pour l'étude de fluides composés, où la description Maxwell–Boltzmann n'est pas valable, par exemple, pour une dense population de particules, pas trop lourdes et a des températures pas trop élevées, et d'une comoposition de nature complexe.
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| 23. |
- Borseth, T.M., et al.
(författare)
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Identification of oxygen and zinc vacancy optical signals in ZnO
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:26, s. 262112-262115
-
Tidskriftsartikel (refereegranskat)abstract
- Photoluminescence spectroscopy has been used to study single crystalline ZnO samples systematically annealed in inert, Zn-rich and O-rich atmospheres. A striking correlation is observed between the choice of annealing ambient and the position of the deep band emission (DBE) often detected in ZnO. In particular, annealing in O2 results in a DBE at 2.35±0.05 eV, whereas annealing in the presence of metallic Zn results in DBE at 2.53±0.05 eV. The authors attribute the former band to zinc vacancy (VZn) related defects and the latter to oxygen vacancy (VO) related defects. Additional confirmation for the VO and VZn peak identification comes from the observation that the effect is reversible when O- and Zn-rich annealing conditions are switched. After annealing in the presence of ZnO powder, there is no indication for the VZn- or VO-related bands, but the authors observe a low intensity yellow luminescence band peaking at 2.17 eV, probably related to Li, a common impurity in hydrothermally grown ZnO.
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| 24. |
- Chalangar, Ebrahim, PhD student, 1984-
(författare)
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Graphene-based nanocomposites for electronics and photocatalysis
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of future electronics depends on the availability of suitable functional materials. Printed electronics, for example, relies on access to highly conductive, inexpensive and printable materials, while strong light absorption and low carrier recombination rates are demanded in photocatalysis industry. Despite all efforts to develop new materials, it still remains a challenge to have all the desirable aspects in a single material. One possible route towards novel functional materials, with improved and unprecedented physical properties, is to form composites of different selected materials.In this work, we report on hydrothermal growth and characterization of graphene/zinc oxide (GR/ZnO) nanocomposites, suited for electronics and photocatalysis application. For conductive purposes, highly Al-doped ZnO nanorods grown on graphene nanoplates (GNPs) prevent the GNPs from agglomerating and promote conductive paths between the GNPs. The effect of the ZnO nanorod morphology and GR dispersity on the nanocomposite conductivity and GR/ZnO nanorod bonding strength were investigated by conductivity measurements and optical spectroscopy. The inspected samples show that growth in high pH solutions promotes a better graphene dispersity, higher doping and enhanced bonding between the GNPs and the ZnO nanorods. Growth in low pH solutions yield samples characterized by a higher conductivity and a reduced number of surface defects.In addition, different GR/ZnO nanocomposites, decorated with plasmonic silver iodide (AgI) nanoparticles, were synthesized and analyzed for solar-driven photocatalysis. The addition of Ag/AgI generates a strong surface plasmon resonance effect involving metallic Ag0, which redshifts the optical absorption maximum into the visible light region enhancing the photocatalytic performance under solar irradiation. A wide range of characterization techniques including, electron microscopy, photoelectron spectroscopy and x-ray diffraction confirm a successful formation of photocatalysts.Our findings show that the novel proposed GR-based nanocomposites can lead to further development of efficient photocatalyst materials with applications in removal of organic pollutants, or for fabrication of large volumes of inexpensive porous conjugated GR-semiconductor composites.
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| 25. |
- Chalangar, Ebrahim, PhD student, 1984-, et al.
(författare)
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Synthesis of Vertically Aligned ZnO Nanorods Using Sol-gel Seeding and Colloidal Lithography Patterning
- 2021
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Ingår i: Nanoscale Research Letters. - Heidelberg : Springer Science and Business Media LLC. - 1931-7573 .- 1556-276X. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Different ZnO nanostructures can be grown using low-cost chemical bath deposition. Although this technique is cost-efficient and flexible, the final structures are usually randomly oriented and hardly controllable in terms of homogeneity and surface density. In this work, we use colloidal lithography to pattern (100) silicon substrates to fully control the nanorods' morphology and density. Moreover, a sol-gel prepared ZnO seed layer was employed to compensate for the lattice mismatch between the silicon substrate and ZnO nanorods. The results show a successful growth of vertically aligned ZnO nanorods with controllable diameter and density in the designated openings in the patterned resist mask deposited on the seed layer. Our method can be used to fabricate optimized devices where vertically ordered ZnO nanorods of high crystalline quality are crucial for the device performance.
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| 26. |
- Chalangar, Seyed Ebrahim, 1984-
(författare)
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Synthesis and Characterization of ZnO/Graphene Nanostructures for Electronics and Photocatalysis
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent rapid development of electronics and electro-optical devices demands affordable and reliable materials with enhanced performance. Forming nanocomposites of already well-known materials is one possible route towards novel functional materials with desirable synergistic enhanced properties. Incompatible chemical properties, mismatched crystal structures and weak bonding interactions between the substances, however, often limit the number of possible nanocomposites. Moreover, using an inexpensive, facile, large-area and flexible fabrication technique is crucial to employ the new composites in industrially viable applications.This thesis focuses on the synthesis and characterization of different zinc oxide/graphene (ZnO/GR) nanocomposites, well suited for optoelectronics and photocatalysis applications. Two different approaches of i) substrate-free random synthesis, and ii) template-assisted selective area synthesis were studied in detail. In the first approach, ZnO nanoparticles/rods were grown on GR. The obtained nanocomposites were investigated for better GR dispersity, electrical conductivity and optical properties. Besides, by adding silver iodide to the nanocomposite, an enhanced plasmonic solar-driven photocatalyst was synthesized and analyzed. In the second approach, arrays of single, vertically aligned ZnO nanorods were synthesized using a colloidal lithography-patterned sol-gel ZnO seed layer. Our demonstrated nanofabrication technique with simple, substrate independent, and large wafer-scale area compatibility improved the alignment and surface density of ZnO nanorods over large selective growth areas. Eventually, we found a novel method to further enhance the vertical alignment of the ZnO nanorods by introducing a GR buffer layer between the Si substrate and the ZnO seed layer, together with the mentioned patterning technique.The synthesized nanocomposites were analyzed using a large variety of experimental techniques including electron microscopy, photoelectron spectroscopy, x-ray diffraction, photoluminescence and cathodoluminescence spectroscopy for in-depth studies of their morphology, chemical and optical properties. Our findings show that the designed ZnO/GR nanocomposites with vertically aligned ZnO nanorods of high crystalline quality, synthesized with the developed low-cost nanofabrication technique, can lead to novel devices offering higher performance at a significantly lower fabrication cost.
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| 27. |
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| 28. |
- Chiragwandi, Zackary, 1968, et al.
(författare)
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Properties of a bio-photovoltaic nano-device
- 2008
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:48, s. 18717-18721
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Tidskriftsartikel (refereegranskat)abstract
- Properties of an on-chip photovoltaic nanodevice are demonstrated. The dyes comprise green florescent proteins(GFP). Dependence of recently reported zero external potential bias (ZEPB) photocurrent (I) on temperature,power, and wavelength (λ) is shown. Correlation between UV-vis spectrum of the GFP and the ZEPB I(λ)of the device is reported. The temperature dependence suggests the ZEPB photocurrent to reflect a liquidcrystal type ordering where the current declines monotonically with increasing temperature. The influence ofan external bias on the photocurrent is demonstrated. The resulting light-induced current is analyzed in termsof resistive and quantum mechanical contributions.
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| 29. |
- Chiragwandi, Zackary, 1968, et al.
(författare)
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Ultraviolet driven negative current and rectifier effect in self assembled green fluorescent protein devices
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:16, s. 162909-1-162909-3
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Tidskriftsartikel (refereegranskat)abstract
- UV induced negative current produced at low voltages is reported in a photocurrent rectifier device consisting of a sensing region between two nano Al/Al2O3 electrodes placed 30 nm apart, employing a droplet of enhanced green fluorescent protein as molecular electrolyte. The current-voltage characteristics are discussed in terms of the properties of the thin Al2O3 scale, the position of the Fermi level, the position of the highest occupied molecular orbital-lowest unoccupied molecular orbital gap, and dispersion of states induced by varying dielectric constants
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| 30. |
- 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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| 31. |
- 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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| 32. |
- David, Denis, et al.
(författare)
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Optical properties from photoelectron energy-loss spectroscopy of low-temperature aqueous chemically synthesized ZnO nanorods grown on Si
- 2019
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Ingår i: Semiconductor Science and Technology. - : Institute of Physics (IOP). - 0268-1242 .- 1361-6641. ; 34:4
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of zinc oxide (ZnO) nanorods (NRs) synthesized by the low-temperature aqueous chemical method on top of silicon (Si) substrate have been investigated by means of photoelectron energy loss spectroscopy (PEELS). The ZnO NRs were obtained by the low temperature aqueous chemical synthesis on top of Si substrate. The measured valence band, the dynamical dielectric functions and optical absorption of the material show a reasonable agreement when the trending and shape of the theoretical calculations are considered. A first-principle calculation based on density functional theory (DFT) was performed using the partially self-consistent GW approximation (scGW(0)) and compared to the experimental results. The application of these two techniques brings a new analysis of the electronic properties of this material. The experimental results regarding the density of states (DOS) obtained for the valence band using x-ray photoelectron spectroscopy (XPS) was found to be consistent with the theoretical calculated value. Due to this consistency, the same wavefunctions was then employed to calculate the dielectric function of the ZnO NRs. The experimentally extracted dielectric function was also consistent with the calculated values.
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| 33. |
- Dawi, E. A., et al.
(författare)
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Ag/AgCl Decorated Ionic Liquid@Tantalum Pentoxide Nanostructures: Fabrication, Photocatalytic Activity, and Cytotoxicity Effects Against Human Brain Tumor Cells
- 2023
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Ingår i: JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS. - : SPRINGER. - 1574-1443. ; 33, s. 2647-2660
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Tidskriftsartikel (refereegranskat)abstract
- Environmental contaminants have become a major concern for human beings due to their adverse effects on drinking water quality. Heterogeneous photocatalysis has been extensively investigated as a potential strategy to minimize the consequences of as-related processes. Using a room-temperature ionic liquid-mediated co-precipitation method, Ag@AgCl nanoparticles were loaded onto tantalum pentoxide to make a plasmonic photocatalyst to remove Congo Red dye. The physicochemical properties of the photocatalysts were characterized by X-ray diffraction powder (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Diffuse Reflectance Spectroscopy (DRS), Fourier-transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), photoluminescence (PL), and nitrogen adsorption-desorption isotherms. The results indicate that 96% of the dye was degraded within 20 min with a rate constant of 0.14 min(-1). The key radicals involved in the photocatalysis, recognized as O-2(center dot-) species, were identified by electron spin resonance (ESR) in the presence of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), as the spin trapping agent. Our findings and quenching experiments elucidates the mechanism of the charge carrier migration. The cytotoxicity activity of the nanostructures was also examined against human brain glioblastoma tumor cells for the first time. A precise analysis of the cell death pathway was conducted using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and caspase activity assays in combination with fluorescence microscopy images. The prepared nanomaterials were found to be promising candidates for treating the organic pollutants and biomedical waste effluents from academic and industrial activities.
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| 34. |
- Elhadi Adam, Rania, et al.
(författare)
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Photocatalytic properties for different metal-oxide nanomaterials
- 2019
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Ingår i: Oxide-based Materials and Devices X. - : SPIE.
-
Konferensbidrag (refereegranskat)abstract
- We here demonstrate the synthesis of different nanostructures, including nanoparticles, nanorods, core-shell structures,and compound metal oxide nanostructures all synthesized by a low temperature chemical process. We furtherinvestigated their photocatalytic properties for degradation of toxic waste and their photochemical efficiency for watersplitting. All the photocatalytic properties as well as the photochemical properties were utilized using sun radiation. Theresults presented indicate huge potential for the investigated processes with positive impact to energy consumption andbenefits for the environment.
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| 35. |
- Elhadi Adam, Rania, et al.
(författare)
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ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation
- 2019
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:15, s. 8271-8279
-
Tidskriftsartikel (refereegranskat)abstract
- Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag2WO4 heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag2WO4 photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag2WO4 was deposited on the ZnO NRs. The Ag2WO4/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag2WO4/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag0) particles from the Ag/Ag2WO4 that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag2WO4/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag2WO4 heterostructure with SPR effect for water oxidation. ER
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| 36. |
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| 37. |
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| 38. |
- Ferreira da Silva, Antonio, et al.
(författare)
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Growth, Optical Characterization and Modelling of ZnO Nanorods on Si, SiC and Macroporous Si Structure
- 2009
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Ingår i: Nanotech 2009 Vol. 3Nanotechnology 2009: Biofuels, Renewable Energy, Coatings, Fluidics and Compact Modeling. - Austin, TX, USA : Nano Science and Technology Institute. - 9781439817841 ; , s. 206-209
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Zinc Oxide (ZnO) and 4H-SiC are prominent materials with large applicability such as optoelectronic nanodevices and for instance ultraviolet detectors. There is lack of more information about optical transitions beyond the indirect band gap energy (BGE) of 4H-SiC and even more for ZnO direct BGE grown on the former material. Using the vapor-liquid-solid and the aqueous chemical growth methods we have grown ZnO nanorods on different substrates, such as quartz, n- and p-type silicon porous silicon and n-type 4H-SiC. The Scanning electron microscopy (SEM) are shown and compared for all samples. We have calculated the absorption and energy gap by employing a first-principle and a full-potential linearized augmented plane-wave (FPLAPW) method within the local density approximation (LDA). The absorption of ZnO nanorods, on different substrates, is lower than that of quartz substrate when photon energy is low. It is shown the strong effect of 4H-SiC on ZnO nanorods. Experiment and theory show a good aggreement when the optical energy gap is considered for both materials.
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| 39. |
- Fu, Ying, 1964, et al.
(författare)
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AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactors
- 1997
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 82:11, s. 5568-5572
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Tidskriftsartikel (refereegranskat)abstract
- By the Schrödinger and Poisson equations, we have theoretically investigated AlGaAs/GaAs and InAlAs/InGaAs single barrier varactors. The energy band structure, carrier distribution, and conduction current are fully exploited for varactor design. We have explained the experimental current-voltage and capacitance-voltage measurements very well. A simple analytical model for energy band structure is derived based on the Schrödinger and Poisson equation calculation. It is found that a barrier structure of 3 nm Al0.3Ga0.7As/3 nm AlAs/3nm Al0.3Ga0.7As for an Al0.3Ga0.7As/GaAs varactor and a barrier structure of 8 nm In0.52Al0.48As/3 nm AlAs/8 nm In0.52Al0.48As for In0.52Al0.48As/In0.47GaAs are optimal for minimal conduction currents.
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| 40. |
- Fu, Ying, 1964, et al.
(författare)
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Capacitance Analysis for AlGaAs/GaAs and InAlAs/InGaAs Heterostructure Barrier Varactor Diodes
- 1998
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 83:3, s. 1457-1462
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Tidskriftsartikel (refereegranskat)abstract
- By self-consistently solving Schro¨dinger and Poissons equations, we have investigated the capacitances of AlGaAs/GaAs and InAlAs/InGaAs heterostructure barrier varactors. When compared with semiclassical particle model, quantum mechanics show that the maximal capacitance of the varactor is saturated when the spacer and barrier are thin. When the spacer and barrier are very thick, both the quantum mechanics and semiconductor particle approach result in the same conclusion, namely, the maximal capacitance is inversely proportional to the sum of the spacer and barrier thicknesses. We have also shown that the maximal capacitance increases for high carrier effective mass.
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| 41. |
- Fu, Ying, 1964, et al.
(författare)
-
Carrier conduction through the quantum barrier in a heterostructure barrier varactor Induced by an AC-Bias
- 2000
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Ingår i: Superlattices and Microstructures. ; 28:2, s. 135-141
-
Tidskriftsartikel (refereegranskat)abstract
- By solving the time-dependent Schrodinger equation, we have studied the quantum transport of a wavepacket in a GaAs/A1GaAs heterostructure barrier varactor (HBV) diode induced by an ac bias. The current conduction of a wavepacket is complicated due to the superposition of many different stationary states. When the oscillating frequency of the external bias is relatively low, the motion of the wavepacket follows the electric field induced by the external bias. When the frequency is too high (over 1000 GHz for the GaAs/A1GaAs HBV structure under investigation), the wavepacket becomes effectively confined by the oscillating bias, and the conduction current is significantly reduced.
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| 42. |
- Fu, Ying, 1964, et al.
(författare)
-
Conductive adhesives
- 2004
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Ingår i: Lead free electronics. ; , s. pp 285-351
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Fu, Y., et al.
(författare)
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Quantum effects and nanofabrications in scaling metal-oxide-semiconductor devices
- 2006. - 1
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Ingår i: Handbook of semiconductor nanostructures and nanodevices. - : American Scientific Publishers. - 1588830780 - 158883073X - 9781588830739 ; , s. 229-256
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Handbook of Semiconductor Nanostructures and Nanodevices is the World's first multivolume handbook covering a wide variety of advanced and emerging developments in the field of semiconductor nanotechnology. Semiconductor materials are the key elements of continued scientific and technological developments made in the fields of electronics, optoelectronics, photonics, and magnetic devices. The five-volume set is an unprecedented encyclopedic reference that covers growth and processing of semiconductor nanostructured materials by MBE, CVD, PVD, electrochemical, and other techniques, all types of III-V, IV, and II-VI semiconductor nanomaterials, nanofabrication by bottom-up and top-down approaches, precise control and uniformity of semiconductor self-assembled nanostructures, quantum dots, and quantum wells, nanowires, nanoclusters, nanocrystals, and nanoparticles, heterojunctions and interface properties, physical, and chemical properties, nanoscale spectroscopic characterization techniques, and applications of semiconductor devices in nanoelectronics, nano-optoelectronics, nanometrology, nanocircuits, nano-imprint lithography, heterojunction devices, laser diodes, LEDs, solar cells, terahertz devices, thermoelectric devices, NEMS/MEMS, optical switches, infrared detectors,, computers, wireless communications, magnetic random access memory (MRAM) and ferroelectric random access memory (FeRAM), spintronic and data storage devices, single-electron transistors, quantum computing devices, .etc. Both experimental and theoretical aspects of semiconductor nanoscience and nanotechnology are covered. It is a must-have handbook for university libraries, research establishments, government laboratories, and high-tech companies engaged in research and development of semiconductors. It is written for a broad range of audience with different backgrounds and educational level, compiling past two decades of pioneering research. It provides in-depth information to research professiona
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| 47. |
- Hölzel, Ralph, et al.
(författare)
-
Holzel et al. Reply
- 2006
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Ingår i: Phys. Rev. Lett.. - 0031-9007 .- 1079-7114. ; 96
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Tidskriftsartikel (refereegranskat)abstract
- A Reply to the Comment by Liming Ying, Dejian Zhou, and Andreas Bruckbauer.
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| 48. |
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| 49. |
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| 50. |
- Jeppson, Kjell, 1947, et al.
(författare)
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Theory of a room-temperature silicon quantum dot device as a sensitive electrometer
- 2004
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Ingår i: Journal of Applied Physics. - Melville, NY : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 95:1, s. 323-326
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Tidskriftsartikel (refereegranskat)abstract
- We consider theoretically the use of a room-temperature silicon quantum dot based device for electrometer applications. The low power device includes two split gates that quantize the electronic energy levels in the emitter and collector regions. The base consists of a silicon quantum dot buried in silicon dioxide. The small size of the dotand quantization of the states in the leads combined to allow the device to operate at room temperature. The nonlinear current-voltage characteristics can be significantly altered by small changes to the potential of the split gates. Power dissipation in the device therefore changes with the split gate voltage, and this can be exploited in electrometerapplications. A simple model of the power dissipated when the device is part of a microwave resonant inductor-resistor-capacitor tank circuit suggests that large changes indevice power can be achieved by changing the gate voltage, thereby forming a measurable signal. We also demonstrate that the power dissipation in the device changes as the base width is varied, and that the current through the device increases exponentially with a decrease in base width. (©2004 American Institute of Physics)
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