| 1. |
- Amin, Gul, et al.
(författare)
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Current-transport studies and trap extraction of hydrothermally grown ZnO nanotubes using gold Schottky diode
- 2010
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Ingår i: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE. - : WILEY-V C H VERLAG GMBH, PO BOX 10 11 61, D-69451 WEINHEIM, GERMANY. - 1862-6300. ; 207:3, s. 748-752
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Tidskriftsartikel (refereegranskat)abstract
- High-quality zinc oxide (ZnO) nanotubes (NTs) were grown by the hydrothermal technique on n-Si substrate. The room temperature (RT) current-transport mechanisms of Au Schottky diodes fabricated from ZnO NTs and nanorods (NRs) reference samples have been studied and compared. The tunneling mechanisms via deep-level states was found to be the main conduction process at low applied voltage but at the trap-filled limit voltage (V-TFL) all traps were filled and the space-charge-limited current conduction was the dominating current-transport mechanism. The deep-level trap energy and the trap concentration for; the NTs were obtained as similar to 0.27 eV and 2.1 x 10(16) cm(-3), respectively. The same parameters were also extracted for the ZnO NRs The deep-level states observed crossponds to zinc interstitials (Zn-i), which are responsible for the violet emission.
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| 2. |
- Bruhn, Benjamin, et al.
(författare)
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Fabricating single silicon quantum rods for repeatable single dot photoluminescence measurements
- 2011
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Ingår i: Physica Status Solidi A-applications and materials science. - Malden : Wiley-VCH Verlagsgesellschaft. - 1862-6319. ; 208:3, s. 631-634
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Tidskriftsartikel (refereegranskat)abstract
- A fabrication method for a matrix pattern of laterally separated silicon quantum rods was developed, consisting of a three-step recipe utilizing electron beam lithography (EBL), reactive ion etching (RIE), and oxidation. Photoluminescence (PL) measurements -images, spectra, and blinking-verified that the presented method results in a high number of luminescing single silicon quantum rods in well defined positions on the sample. These are suitable for single dot spectroscopy and repeatable measurements, even using different measurement methods and instruments. [GRAPHICS] Colorized scanning electron microscope images of undulating silicon nanowalls for controlled single quantum rod fabrication.
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| 3. |
- Buniatyan, V. V., et al.
(författare)
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pH-sensitive properties of barium strontium titanate (BST) thin films prepared by pulsed laser deposition technique
- 2010
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Ingår i: Physica Status Solidi (A) Applications and Materials Science. - : Wiley. - 1862-6319 .- 1862-6300. ; 207:4, s. 824-830
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Tidskriftsartikel (refereegranskat)abstract
- pH sensitive properties of barium strontium titianate (BST) high k thin films as alternative gate material for field-effect capacitive (bio-) chemical sensors based on an electrolyte-insulator semiconductor system have been investigated. The BST films of different composition (Ba0.3Sr0.69TiO3, Ba0.25Sr0.75TiO3 and MG doped Ba0.8Sr0.2Mg0.1Ti0.9O3 were deposited by pulsed laser deposition technique from targets farbicated by self-propagating high-temperatures synthesis. The realised sensors have been electrochemically characterised by means of impedance-spectroscopy, capacitance-voltage and constant-capacitance method. The sensors possess a Nernstian-like pH sensitivity in the concentration range between pH 3 and 11 with a response time of 5-10 s. An equivalent circuit model for the BST-based capacitive field-effect sensor is discussed.(C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 4. |
- Carvalho, Alexandra, et al.
(författare)
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Light induced degradation in B doped Cz-Si solar cells
- 2012
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 209:10, s. 1894-1897
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Tidskriftsartikel (refereegranskat)abstract
- We analyse the formation energy of interstitial boron (Bi) and the properties of the defect resulting from its association with an oxygen dimer (BiO2i) to evaluate the possibility that it may be the slow-forming centre responsible for the light-induced degradation of B-doped Si solar cells. However, we find that the formation energy of Bi is too high, and therefore its concentration is negligible. Moreover, we find that the lowest energy form of BiO2i is a shallow donor, and the deep donor form is high in energy. Lowest energy structure of the BiO2i defect.
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| 5. |
- Carvalho, Alexandra, et al.
(författare)
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P-doping of Si nanoparticles : the effect of oxidation
- 2012
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 209:10, s. 1847-1850
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Tidskriftsartikel (refereegranskat)abstract
- The radial dependence of the formation energy of substitutional phosphorus in silicon nanoparticles covered by an amorphous oxide shell is analysed using local density functional theory calculations. It is found that P+ is more stable at the silicon core. This explains the experimental observation of segregation of phosphorus to the Si-rich regions in a material consisting of Si nanocrystals embedded in a SiO2 matrix [Perego et al., Nanotechnology 21, 025602 (2010)]. Formation energy of positively charged substitutional phosphorus in a 1.5 nm diameter Si nanoparticle covered by a ∼2 nm-thick amorphous SiO2 shell, as a function of its distance to the centre.
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| 6. |
- Chey, Chan Oeurn, et al.
(författare)
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Fast synthesis, morphology transformation, structural and optical properties of ZnO nanorods grown by seed-free hydrothermal method
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 211:11, s. 2611-2615
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Tidskriftsartikel (refereegranskat)abstract
- A fast and low cost seed-free hydrothermal synthesis method to synthesize zinc oxide (ZnO) nanorods with controllable morphology, size and structure has been developed. Ammonia is used to react with water to tailor the ammonium hydroxide concentration, which provides a continuous source of OH− for hydrolysis and precipitation of the final products. Hence, allowing ZnO nanorods to growth on large areas of metal (Au and Ag coated glass), p-type Si and organic flexible (PEDOT: PSS) substrates. Increasing the growth time, the morphology transforms from pencil-like to hexagonal shape rod-like morphology. Within one hour the length of the ZnO nanorods has reached almost 1 µm. The optical characteristics has shown that the grown ZnO nanorods are dominated by two emission peaks, one is in the UV range centered at 381 nm and other one with relatively high intensity appears in the visible range and centered at 630 nm. While the growth duration was increased from 2 h to 6 h, the optical band gap was observed to increase from 2.8 eV to 3.24 eV, respectively. This fast and low cost method is suitable for LEDs, UV-photodetector, sensing, photocatalytic, multifunctional devices and other optoelectronic devices, which can be fabricated on any substrates, including flexible and foldable substrates.
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| 7. |
- Gavagnin, Marco, et al.
(författare)
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Magnetic force microscopy study of shape engineered FEBID iron nanostructures
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 211:2, s. 368-374
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Tidskriftsartikel (refereegranskat)abstract
- The capability to control matter down to the nanoscale level in combination with the novel magnetic properties of nanomaterials have attracted increasing attention in the last few decades due to their applications in magnetic sensing, hard disc data storage and logic devices. Therefore, many efforts have been devoted to the implementation of both nanofabrication methods as well as characterization of magnetic nanoelements. In this study, Fe-based nanostructures have been synthesized on Si(100) by focused electron beam induced deposition (FEBID) utilizing iron pentacarbonyl as precursor. The so obtained nanostructures exhibit a remarkably high iron content (Fe>80at.%), expected to give rise to a ferromagnetic behaviour. For that reason, magnetic force microscopy (MFM) analyses were performed on the obtained FEBID Fe nanostructures. Moreover, object oriented micromagnetic framework (OOMMF) magnetic simulations have been executed to study the influence of the geometry on the magnetic properties of iron single-domain nanowires. FEBID is a mask-less nanofabrication method based on the injection of precursor gas molecules in proximity of the deposition area where their decomposition is locally induced by a focused electron beam.
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| 8. |
- Hussain, Mushtaque, et al.
(författare)
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The improved piezoelectric properties of ZnO nanorods with oxygen plasma treatment on the single layer graphene coated polymer substrate
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlag. - 1862-6300 .- 1862-6319. ; 211:2, s. 455-459
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Tidskriftsartikel (refereegranskat)abstract
- The step towards the fabrication of nanodevices with improved performance is of high demand; therefore, in this study, oxygen plasma treated ZnO nanorods based piezoelectric nanogenerator is developed on the single layer graphene coated PET flexible polymer substrate. ZnO nanorods on the single layer graphene are grown by hydrothermal growth method and the structural study is carried out by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The piezoelectric properties of ZnO nanorods with and without plasma treatment were investigated by atomic force microscopy (AFM). The oxygen plasma treated sample of ZnO nanorods showed significant increase in the piezoelectric potential which could be due to the decrease in the defects levels in the ZnO and also increase in the mechanical properties of ZnO nanorods. Furthermore X-ray photoelectron spectroscopy (XPS) confirms that the filling of vacancies by oxygen in the matrix of ZnO using oxygen plasma treatment has gave an enhanced piezoelectric potential compared to the sample of ZnO nanorods not treated with oxygen plasma. In addition to XPS experiment, cathodoluminescence (CL) technique was used for the determination of defect level in the ZnO nanorods after the treatment of oxygen plasma and the obtained information supported the XPS data of oxygen plasma treatment sample by showing the decreased level of defect levels in the prepared sample. From the XPS and CL studies, it is observed that the defect level has significant influence on the piezoelectric potential of the ZnO nanostructures.
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| 9. |
- Kataria, S., et al.
(författare)
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Chemical vapor deposited graphene : From synthesis to applications
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 211:11, s. 2439-2449
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Forskningsöversikt (refereegranskat)abstract
- Graphene is a material with enormous potential for numerous applications. Therefore, significant efforts are dedicated to large-scale graphene production using a chemical vapor deposition (CVD) technique. In addition, research is directed at developing methods to incorporate graphene in established production technologies and process flows. In this paper, we present a brief review of available CVD methods for graphene synthesis. We also discuss scalable methods to transfer graphene onto desired substrates. Finally, we discuss potential applications that would benefit from a fully scaled, semiconductor technology compatible production process.
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| 10. |
- Khranovskyy, Volodymyr, et al.
(författare)
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Effect of Ag doping on the microstructure and photoluminescence of ZnO nanostructures
- 2014
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlag. - 1862-6300 .- 1862-6319. ; 211:9, s. 2109-2114
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Tidskriftsartikel (refereegranskat)abstract
- ZnO nanostructures were obtained by metal-organic chemical vapor deposition via Ag catalyst-assisted growth in a temperature range of 200-500 degrees C. Growth at temperatures above 500 degrees C resulted in vertically aligned ZnO nanorods (NLs). Ag incorporation into ZnO up to 0.4 at.% promoted creation of basal plane stacking fault (BSF) defects and corrugation of the side facets of the NLs. The presence of BSFs give rise to an additional photoluminescence peak with a wavelength of similar to 386 nm, which is slightly red-shifted compared to the commonly observed NBE emission at similar to 375 nm. The observed emission was found to be specifically observed from the side facets of the NLs. It is suggested that this emission is due to a high concentration of BSFs in the ZnO as a result of an incorporation of Ag as acceptor dopant. [GRAPHICS] SEM image of an Ag-doped ZnO nanorod with corrugated side facets. The observed corrugation is accompanied by a high concentration of basal plane stacking faults.
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