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Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | Thiwawong T.,King Mongkut's University of Technology Thonburi | Thiwawong T.,Nanotec Excellence Center on Nanoelectronic Devices | And 2 more authors.
Organic Electronics: physics, materials, applications | Year: 2016

This research reported the transparent non-volatile write-once-read-many-times (WORM) memory behaviors of memory devices based on zinc oxide nanoparticles (ZnO NPs) embedded in an insulating poly(ethylene-co-vinyl acetate) (EVA), sandwiched between two ITO-coated flexible polyethylene naphthalate (PEN) substrates. The memory devices were fabricated employing a thermal roll lamination technique with the laminated-structure of PEN/ITO/EVA:ZnO NPs/ITO/PEN. The average transmittance of the laminated memory device was over 70% for an optical visible range of 400-800 nm. The maximum ON/OFF current ratio for the memory device was about 103. In addition, a reliability study for continuous read operations in a long time memory device is presented. The conductance switching mechanisms of the laminated memory device were analyzed using theoretical models on the basis of the experimental data. © 2016 Elsevier B.V. All rights reserved.


Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | Chaithanatkun N.,King Mongkut's University of Technology Thonburi | Chaithanatkun N.,Nanotec Excellence Center on Nanoelectronic Devices | And 2 more authors.
Current Applied Physics | Year: 2016

We reported on the influence of the structural properties of zinc oxide nanoparticles (ZnO NPs) on electrical bi-stable device based on an aluminum/poly(9-vinylcarbazole):ZnO NPs/indium-tin oxide structure. ZnO NPs were synthesized by simple precipitation method with different annealing temperatures. When annealing temperature was increased, the ZnO NPs crystallite increased and the ZnO NPs gradually changed shape from nanostar-like to nanospherical. The structural parameters, such as the crystallite size of ZnO NPs and dislocation density, can be calculated from the XRD spectra. The effect of ZnO NPs annealing temperature on memory properties can be measured by current-voltage characteristics and retention time measurements. The maximum ON/OFF current ratio for the memory devices was about 103 and the devices exhibited the Write-Once, Read-Many (WORM) memory type. The operating mechanisms of the memory device were analyzed using theoretical models, in which electrons trapping in the ZnO NPs and electrons tunneling among a PVK matrix by direct tunneling process were discussed. © 2016 Elsevier B.V.


Keeratithiwakorn P.,King Mongkut's University of Technology Thonburi | Keeratithiwakorn P.,Nanotec Excellence Center on Nanoelectronic Devices | Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | And 4 more authors.
Advanced Materials Research | Year: 2013

In this work, we report on the frequency-impedance characteristics of dye-doped organic material. The device structure is glass substrate/indium tin oxide/DCM:Alq3/Aluminum 100 nm. The influence of doping concentraion has been investigated by impedance spectroscopy. The impedance characteristics of the dye-doped organic material can be modelled by simply adopting the conventional equivalent circuit with the simple combination of resistors and capacitor network. The variation of bulk resistance with applied bias voltage as a result of the Space Charge Limited Conduction (SCLC) mechanism for charge conduction. © (2013) Trans Tech Publications, Switzerland.


Thiwawong T.,King Mongkut's University of Technology Thonburi | Thiwawong T.,Nanotec Excellence Center on Nanoelectronic Devices | Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | And 2 more authors.
Advances in Materials Science and Engineering | Year: 2013

In this work, thin film of silver nanoparticles for humidity sensor application was deposited by electrostatic spray deposition technique. The influence of the deposition times on properties of films was studied. The crystal structures of sample films, their surface morphology, and optical properties have been investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and UV-VIS spectrophotometer, respectively. The crystalline structure of silver nanoparticles thin film was found in the orientation of (100) and (200) planes of cubic structure at diffraction angles 2θ = 38.2° and 44.3°, respectively. Moreover, the silver nanoparticles thin films humidity sensor was fabricated onto the interdigitated electrodes. The sensor exhibited the humidity adsorption and desorption properties. The sensing mechanisms of the device were also elucidated by complex impedance analysis. © 2013 Thutiyaporn Thiwawong et al.


Chansaengsri K.,King Mongkut's University of Technology Thonburi | Chansaengsri K.,Nanotec Excellence Center on Nanoelectronic Devices | Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | And 4 more authors.
Key Engineering Materials | Year: 2016

In this work, cobalt oxide thin films were prepared by electrostatic spray deposition (ESD) technique on glass substrate. The influence of the annealing temperature on properties of cobalt oxide film was investigated. The structural, optical and morphology of cobalt oxide thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Visible spectrophotometer, scanning electron microscope, respectively. The crystalline parameters such as crystalline size of films can be obtained from XRD spectra. Phase transformation due to the different annealing temperature in cobalt oxide film has been observed. Moreover, at the higher annealing temperature, the optical band gap in cobalt oxide films were shifted to lower value due to the change in crystalline size and the defect sites in films. © 2016 Trans Tech Publications, Switzerland.


Chansaengsri K.,King Mongkut's University of Technology Thonburi | Chansaengsri K.,Nanotec Excellence Center on Nanoelectronic Devices | Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | And 4 more authors.
Key Engineering Materials | Year: 2016

In this work, cobalt oxide thin films were prepared by electrostatic spray deposition (ESD) technique. The influence of the substrate temperatures on properties of film was investigated. Phase transformation of cobalt oxide thin films due to the effect of different substrate temperature was also observed. Cyclic voltammetry was used to measure the performance of cobalt oxide supercapacitor. At higher substrate temperature, the cobalt oxide thin films exhibit the high specific capacitance due to the effect of phase transformation in cobalt oxide films. © 2016 Trans Tech Publications, Switzerland.


Chaithanatkun N.,King Mongkut's University of Technology Thonburi | Chaithanatkun N.,Nanotec Excellence Center on Nanoelectronic Devices | Onlaor K.,King Mongkut's University of Technology Thonburi | Onlaor K.,Nanotec Excellence Center on Nanoelectronic Devices | And 4 more authors.
Key Engineering Materials | Year: 2016

In this work, zinc oxide (ZnO) nanoparticles were synthesized by simple chemical precipitation method in the present of zinc nitrate as zinc precursor and sodium hydroxide as hydroxide precursor. The vitamin C was used as modifier media to modify the structural properties of ZnO nanoparticles. The microstructures of ZnO nanoparticles were characterized by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Selected area electron diffraction (SAED) patterns showed that polycrystalline hexagonal phase of ZnO. The defects and impurity contents in nanoparticles were investigated by Fourier transform infrared (FT-IR) spectroscopy. The results show few carboxylate and hydroxyl impurities for larger particles when addition modifier increases. Surface areas of nanoparticles were measured by Brunauer Emmett Teller (BET) method. In addition, the results exhibited the dramatically change in structural properties of ZnO nanoparticles due to the effect of vitamin C. © 2016 Trans Tech Publications, Switzerland.


Chaithanatkun N.,King Mongkut's University of Technology Thonburi | Chaithanatkun N.,Nanotec Excellence Center on Nanoelectronic Devices | Chantarawong D.,King Mongkut's University of Technology Thonburi | Chantarawong D.,Nanotec Excellence Center on Nanoelectronic Devices | And 8 more authors.
2015 IEEE 10th International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2015 | Year: 2015

Thin films of zinc oxide nanoparticles (ZnO NPs) for bistable device was prepared by electrostatic spray deposition technique based on an indium-tin oxide/ZnO NPs/aluminum (ITO/ZnO NPs /Al) structure. The characterizations of ZnO NPs films were performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). The influence of the deposition time on properties of films was also investigated. Moreover, the effect of deposition time on the bistable properties can be performed by current-voltage (I-V) measurements. The conduction mechanism of the bistable device was analyzed by theoretical model. © 2015 IEEE.


Chaithanatkun N.,King Mongkut's University of Technology Thonburi | Chaithanatkun N.,Nanotec Excellence Center on Nanoelectronic Devices | Chantarawong D.,King Mongkut's University of Technology Thonburi | Chantarawong D.,Nanotec Excellence Center on Nanoelectronic Devices | And 8 more authors.
2015 IEEE 10th International Conference on Nano/Micro Engineered and Molecular Systems, NEMS 2015 | Year: 2015

In this work, zinc oxide nanoparticles (ZnO NPs) was prepared by chemical precipitation process. To study the influence of the ascorbic acid on properties of ZnO nanoparticles, the ascorbic acid was added to precursor solution at different molar ratio of ascorbic acid (AA) and zinc during the synthesis process. The characterizations of ZnO nanoparticles were performed using X-ray diffraction (XRD), Raman spectroscope, and field emission scanning electron microscopy (FE-SEM). The effect of ascorbic acid on the structural properties of ZnO NPs was investigated. © 2015 IEEE.

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