Growth characteristics of ultra long double-ended acicular ZnO synthesized by a hydrothermal process

Tzeng, Shi-Kai; Hon, Min–Hsiung; Leu, Ing‐Chi

doi:10.1016/j.jcrysgro.2009.08.015

Cited by 10 publications

(5 citation statements)

References 25 publications

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“…For example, PVA membranes have been used in the artificial pancreas, hemodialysis, and implantable biomaterials [4,5]. Recently, a considerable amount of work has been reported on PVA and its composite PVA films [6][7][8][9][10][11][12][13]. TiO 2 is well known as a matter with strong redox ability, and used for water or air purification and photoelectrochemical cell, due to its cheapness, nontoxicity and high photocatalytic activity.…”

Section: Introductionmentioning

confidence: 99%

Nano Composite PVA-TiO<sub>2</sub> Thin Films for OTFTs

Sathish¹,

Shekar²,

Bhavyasree³

2013

AMR

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Pure PVA and composite thin films of poly vinyl alcohol (PVA)/Titanium dioxide (TiO2) were prepared on pre-cleaned glass substrates by Dip Coating Technique (DCT) and Metal Organic Deposition Technique (MODT). EDS and FTIR spectrum were used to identify the composition of the prepared films. The vibrational peaks observed at 1260 cm-1 and 851 cm-1 are assigned to C–C stretching and CH rocking of PVA. The characteristic band appearing at 1432 cm-1 is assigned to C–H bend of CH2 of PVA. The bands observed around 847 cm-1 and 601cm-1 belong to the asymmetric stretching of Ti–O–Ti groups. The last band at 460 cm-1 is due to the bending mode of Ti–O–Ti. The bands covered by Ti-O were located at 540, 700 and 950 cm-1. From the FTIR spectra, it is observed that some of the peaks of composite films were shifted and some of them were disappeared with respect to the pure compounds. This results manifested the conclusion about the specific interactions in composite polymer matrices and hence the complexation. Thus, complex formation in the composite polymer matrices has been confirmed from this analysis. The thickness of the coated films were measured by using an electronic thickness measuring instrument (Tesatronic-TTD-20), gravimetric method and cross checked by optical spectrophotometer. XRD spectra indicated the amorphous nature of the films. Surface morphology of the coated films was studied by scanning electron microscope (SEM). The surface revealed no pits and pin holes on the surface. Both as grown and annealed films showed predominantly amorphous nature. The observed surface morphology and thermal stability indicated that these films could be used as dielectric layer in organic thin film transistors.

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Section: Introductionmentioning

confidence: 99%

Nano Composite PVA-TiO<sub>2</sub> Thin Films for OTFTs

Sathish¹,

Shekar²,

Bhavyasree³

2013

AMR

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“…The ZnO NWs used in this study were synthesized through a hydrothermal process, and the detailed experimental setup has been described elsewhere. 16 Blank ZnO NWs-based PDs were fabricated by dielectrophoresis with an alternating electric field of 2 × 10 5 V/m (frequency: 20 MHz) in which the electrodes (Au/Cr) consisted of two 10-μm-wide fingers pointed head to head at a distance of 10 μm. The electric field induces the charge separation of ZnO NWs, and the resulting polarization generates a dipole moment and aligns the NWs parallel with the field lines.…”

Section: Methodsmentioning

confidence: 99%

Improving the Performance of a Zinc Oxide Nanowire Ultraviolet Photodetector by Adding Silver Nanoparticles

Tzeng

Hon

Leu

2012

J. Electrochem. Soc.

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A significant enhancement in the performance of a ZnO nanowire-based UV detector has been achieved through fabricating a Ag/ZnO heterostructure by a photoreduction reaction. This enhancement is due to a Schottky barrier at the interface of Ag and ZnO because of the formation of a thin AgO x layer. An efficient and low-working-temperature method was proposed for eliminating the familiar persistent photoconductivity in ZnO nanostructure-based photodetectors, and the approach can be widely applied to other photodetectors employing the Schottky barrier phenomenon.

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“…16 PVA ͑0.14 g͒ was mixed with 5 mL of zinc acetate dihydrate methyl solution ͑0.08 M͒ and stirred for 60 min to promote the reaction of PVA with the Zn 2+ ions, and then 10 mL of aqueous Me 4 NOH solution ͑2.5 M͒ was added and stirred for another 30 min. The solution was transferred to a Teflon-lined stainless steel autoclave and heated at 150°C for 24 h. The average DEP process.-The Schottky diodes using ZnO NWs as the semiconductor material were fabricated through the DEP process and the schematic structure of the diode is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Synthesis.-The ZnO NWs used in this work were synthesized based on the previous study. 16 PVA ͑0.14 g͒ was mixed with 5 mL of zinc acetate dihydrate methyl solution ͑0.08 M͒ and stirred for 60 min to promote the reaction of PVA with the Zn 2+ ions, and then 10 mL of aqueous Me 4 NOH solution ͑2.5 M͒ was added and stirred for another 30 min. The solution was transferred to a Teflon-lined stainless steel autoclave and heated at 150°C for 24 h. The average length and diameter of the as-synthesized NWs were around 52.3 m and 250 nm, respectively.…”

Section: Methodsmentioning

confidence: 99%

Improvement in the Photocurrent to Dark Current Contrast Ratio of ZnO/Au Schottky Photodetector with PMMA Microlens Arrays

Tzeng

Hon

Leu

2010

J. Electrochem. Soc.

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A method is proposed to improve the photocurrent to dark current contrast ratio for the ZnO nanowire/Au Schottky barrier diode fabricated using dielectrophoresis to align the nanowires. Because the leakage current would lead to a large background noise, a poly͑methyl methacrylate͒ ͑PMMA͒ layer is first employed as the passivation layer to cap on the surface of the ZnO nanowire Schottky diode; furthermore, the microlens array ͑MLA͒ structures are added to improve the light trapping effect and to magnify the probability of the photons to be absorbed by ZnO nanowires. After depositing the PMMA capping layer, the leakage current can be reduced by more than 10 3 times, whereas the contrast ratio can be increased from 3.4 ϫ 10 to 6.7 ϫ 10 2 at Ϫ1.0 V after the MLA structures are added on the diode.Zinc oxide is one of the most promising materials for fabricating high sensitivity UV detectors because it has a wide direct bandgap ͑3.37 eV at room temperature͒ and a high resistance to high energy radiation, 1 making it a candidate for space application. ZnO has given rise to a great interest in recent years, including the study of diverse synthetic methods, various processing technologies, and fabrication of versatile functional devices. The devices based on ZnO nanowires ͑NWs͒, such as optically pumped nanolaser, light emitting diode, and transistor, have been demonstrated due to the combination of particular structural and semiconducting properties of ZnO nanomaterials. There are different types of semiconductor photodectors: photoconductors, Schottky barrier, metal-insulatorsemiconductor structures, and p-n and p-i-n photodiodes. The detectors that are mentioned above are all operated in the process that the photogenerated carriers interact with the external circuit to provide the output signal through carrier transport. Photoconductors are fabricated by depositing electrodes with ohmic contacts at both ends of a semiconductor slab. For a sample with a long lifetime and short electrode spacing, the gain can be substantially greater than unity. However, the photoconductors show a very nonlinear response with illuminating power, and a very slow nonexponential transient response. 2,3 The metal-insulator-semiconductor structure is designed to obtain a high breakdown voltage and large barrier height which could improve the response. 4 The photodetectors based on the Schottky junction are desirable due to their ability to operate at high switch speeds. Furthermore, to improve the contrast ratio ͑ratio of photo to dark current͒ of the photodiodes, the diodes are often operated in reverse bias to reduce the probability of recombination of the photogenerated electron-hole pairs. The width of the depletion region can be optimized by tuning the reverse bias. For high frequency operation, the depletion region must be kept thin to reduce the transit time. To increase the quantum efficiency, the depletion layer must be sufficiently thick to allow a large fraction of incident light to be absorbed. Because the charge distribution of a...

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Growth characteristics of ultra long double-ended acicular ZnO synthesized by a hydrothermal process

Cited by 10 publications

References 25 publications

Nano Composite PVA-TiO<sub>2</sub> Thin Films for OTFTs

Nano Composite PVA-TiO<sub>2</sub> Thin Films for OTFTs

Improving the Performance of a Zinc Oxide Nanowire Ultraviolet Photodetector by Adding Silver Nanoparticles

Improvement in the Photocurrent to Dark Current Contrast Ratio of ZnO/Au Schottky Photodetector with PMMA Microlens Arrays

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