Synthesis and properties of ZnO nano-ribbon and comb structures

ZnO is of great interest for photonic applications due to its wide band gap (3.37 eV) and large exciton binding energy (60 meV). A large variety of fabrication methods and nanostructure morphologies was reported up to date for this material. Obtained morphologies include nanobelts or nanoribbons, nanowires, nanorods, tetrapod nanostructures, etc. Novel nanostructures like hierarchical nanostructures, nanobridges and nanonails have also been fabricated. In this work, we report a simple method for fabrication of nanoribbon and nanocomb structures. The structures are fabricated by evaporation of a mixture of ZnO and carbon nanotubes (CNT) at 1050°C, and the deposition products have been collected on Si substrates in the temperature range 750-800°C. The growth mechanism of obtained structures is discussed. © 2005 American Institute of Physics.published_or_final_versio

Growth of SiO x nanowire bunches cocatalyzed with Ga and Ni

Si Ox nanowire bunches were fabricated on Ni (N O3) 2* 6 H2 O solution-coated Si(111) substrates in a chemical vapor deposition system in the presence of Ga and under the flow of Ar and N H3 gases. The roles of nickel nitrate hydrate, gallium, and ammonia in the formation of Si Ox nanowire bunches were investigated. It was found that Ni and Ga act as catalysts for the growth, while nickel nitrate hydrate also serves as a source of oxygen. The growth mechanisms of different nanowire structures obtained by varying the fabrication conditions are discussed. © 2005 American Institute of Physics.published_or_final_versio

Growth of N, N′-di(naphthalene-1-yl)-N, N′-diphenyl-benzidine dome structures

N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine samples exhibiting interesting nano/microstructure were fabricated by thermal evaporation in a tube furnace under Ar gas flow. We investigated the influence of the substrate type, substrate temperature, source temperature, and the gas flow rate on the obtained morphology. The deposited material was investigated using scanning electron microscopy, x-ray diffraction, and photoluminescence. We found that the substrate temperature was the factor which significantly affected the obtained morphology, while other factors such as substrate type, source temperature, and gas flow mainly affected the size distribution of the features but not the type of morphology observed. © 2005 American Institute of Physics.published_or_final_versio

Doping of GaN by Mg diffusion

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ZnO nanostructures prepared from ZnO:CNT mixtures

Due to its wide band gap (3.37 eV) and large exciton binding energy (60 meV), ZnO is of great interest for photonic applications. A number of different morphologies, such as nanobelts, nanowires, tetrapod nanostructures, tubular nanostructures, hierarchical nanostructures, nanobridges, nanonails, oriented nanorod arrays, nanoneedles, nanowalls, and nanosheets, were reported. A range of synthesis methods for fabrication of ZnO nanostructures was reported as well. A common method is evaporation from mixture of ZnO and carbon, which is usually in the form of graphite. In this work, we studied the morphology of the ZnO nanostructures fabricated from the mixture of ZnO (micron-sized and nanoparticles) and carbon (graphite, single-wall carbon nanotubes). When graphite and ZnO powders were used, tetrapod structures were obtained. If one of the reactants was nanosized, the diameter of the tetrapod arms was no longer constant. Finally, when both reactants were nanosized, novel morphologies were obtained. We studied the dependence of the morphology on the amount of starting material and the type of carbon used. The ZnO nanostructures were studied using field emission scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and X-ray diffraction. Growth mechanism and factors affecting the morphologies are discussed.published_or_final_versio

Green photoluminescence in ZnO nanostructures

In photoluminescence (PL) spectrum of ZnO, typically one or more peaks in the visible spectral range due to defect emission can be observed in addition to one UV peak due to band edge emission. The origin of the defect emission is controversial and several mechanisms have been proposed. In this work, we fabricated ZnO nanostructures with different methods (evaporation and chemical synthesis). We found that the preparation method influences the peak position of the defect emission. Different hypotheses for the origin of the green emission in our nanostructured samples are discussed. © 2005 American Institute of Physics.published_or_final_versio

Dissection of powdery mildew resistance uncover different resistance types in the Triticum turgidum L. gene pool

BACKGROUND: The aim of the present study was to compare the clinical and cosmetic results of transvaginal hybrid cholecystectomy (TVC), single-port cholecystectomy (SPC), and conventional laparoscopic cholecystectomy (CLC). Recently, single-incision laparoscopic surgery and natural orifice transluminal endoscopic surgery have been developed as minimally invasive alternatives for CLC. Few comparative studies have been reported. METHODS: Female patients with symptomatic gallstone disease who were treated in 2011 with SPC, TVC, or CLC were entered into a database. Patients were matched for age, body mass index, and previous abdominal surgery. After the operation all patients received a survey with questions about recovery, cosmesis, and body image. Results : A total of 90 patients, 30 in each group, were evaluated. Median operative time for CLC was significantly shorter (p < 0.001). There were no major complications. Length of hospital stay, postoperative pain, and postoperative complications were not significantly different. The results for cosmesis and body image after the transvaginal approach were significantly higher. None of the sexually active women observed postoperative dyspareunia. CONCLUSIONS: Both SPC and TVC are feasible procedures when performed in selected patients. CLC is a faster procedure, but other clinical outcomes and complication rates were similar. SPC, and especially TVC, offer a better cosmetic result. Randomized trials are needed to specify the role of SPC and TVC in the treatment of patients with symptomatic gallstone disease

Different origins of visible luminescence in ZnO nanostructures fabricated by the chemical and evaporation methods

Zinc oxide nanostructures were fabricated using chemical and thermal evaporation methods. Scanning electron microscopy (SEM), x-ray diffraction, photoluminescence, and electron paramagnetic resonance (EPR) spectroscopy were used to study the properties of fabricated nanostructures. The nanostructures fabricated by evaporationg methods exhibited green PL from surface centers. The results show that the luminescence in the visible region has different peak positions in samples prepared by chemical and evaporation methods.published_or_final_versio

Magnetic properties of Mn doped ZnO tetrapod structures

Author name used in this publication: C. Surya2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe