Korakot Onlaor

A Humidity Sensor Based on Silver Nanoparticles Thin Film Prepared by Electrostatic Spray Deposition Process

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.

The Influence of Annealing Temperature on Structural Properties of Zinc Oxide Nanoparticles Synthesized by Precipitation Method

In the present work, the precipitation method was applied to prepare zinc oxide nanoparticles in the presence of zinc nitrate and potassium hydroxide as precursor solutions. The influence of annealing temperature on the properties such as structural and morphological of zinc oxide nanoparticles were performed by X-ray diffraction technique, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy. The effects of annealing temperature on the crystallite size of zinc oxide nanoparticles have investigated. The XRD results represented that the zinc oxide nanoparticles exhibits high crystallinity of hexagonal wurtzite crystal structure. The average crystallite size of nanoparticles increased from 18 to 31 nm when the annealing temperature had increased. The morphology images show that the nanoparticles in this work were spherical in shape. Raman and FT-IR spectra confirm that the quality of Zn-O vibrational mode is stronger at higher annealing temperature.

Electrical bistable properties of ZnO nanoparticles thin film prepared by electrostatic spray deposition technique

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.

Charge Transfer Mechanism in Organic Memory Device

In this paper, the conduction mechanism in organic bistable memory device was investigated by both experimental and theoretical method. The current voltage (J-V) characteristics showed the electrical bistable properties between an initial low-conductivity state and a high-conductivity state upon application of an external electric field at room temperature. The current transition exhibited a very narrow voltage range that causes an abrupt increase of current. The on-state and the off-state were proposed by space-charge-limited current and thermionic emission model, respectively. That supported by the experimental data to explained the charge transfer mechanism in organic memory device.

Preparation of copper doped zinc oxide nanoparticles by precipitation process for humidity sensing device

In this work, nanoparticles of copper-doped zinc oxide were synthesized using the precipitation process at different copper doping molars. The structure of the synthesized nanoparticles was examined by X-ray diffraction and X-ray photoelectron spectroscopy. From the results, it was indicated that the nanoparticles were composed of mixed copper oxide-zinc oxide. To fabricate the humidity sensor, the nanoparticles were dispersed in ethanol and deposited on an electrode using the electrostatic spray deposition technique. The humidity sensing behavior was assessed at various humidity levels in a closed vessel of saturated salt solution. Moreover, the response times for the device were recorded. The Cole-Cole plot of the real and imaginary parts of impedance could be useful for description of the equivalent circuit that indicates the mechanism for humidity sensing behavior.In this work, nanoparticles of copper-doped zinc oxide were synthesized using the precipitation process at different copper doping molars. The structure of the synthesized nanoparticles was examined by X-ray diffraction and X-ray photoelectron spectroscopy. From the results, it was indicated that the nanoparticles were composed of mixed copper oxide-zinc oxide. To fabricate the humidity sensor, the nanoparticles were dispersed in ethanol and deposited on an electrode using the electrostatic spray deposition technique. The humidity sensing behavior was assessed at various humidity levels in a closed vessel of saturated salt solution. Moreover, the response times for the device were recorded. The Cole-Cole plot of the real and imaginary parts of impedance could be useful for description of the equivalent circuit that indicates the mechanism for humidity sensing behavior.

Humidity Sensor Based on Graphene Oxide Film Prepared by Simple Drop-Casting Process

In this work, the film of graphene oxide was deposited by drop-casting process for humidity sensor device. The structural property of graphene oxide film was performed by Raman spectroscopy. The humidity device was fabricated onto the indium-tin oxide transparent electrode. The device exhibited the adsorption and desorption behavior of humidity in range of 23-93%RH. The complex impedance measurement was used to explain the mechanisms of the humidity device. The equivalent circuit model of the device has been demonstrated.

Effect of Anodizing Voltage on Anodic Titanium Dioxide (ATO) Growth Based on an Ethylene Glycol Solution Containing NH4F

We reported on the influence of applied voltage on the surface morphology of anodic titanium dioxide (ATO) thin films. At first, titanium (Ti) thin films were prepared by DC-magnetron sputtering for use as a base material in the anodization process. The titanium dioxide (TiO2) nanoporous ATO was fabricated by the anodization process from the Ti thin film, with different applied voltages from 20 V to 60 V in an electrolyte based on an ethylene glycol containing NH4F. Pore size distribution of ATO thin films can be varied from 20-50 nm by increasing the applied voltage, while the thickness of the film also increases. In addition, to observe the effect of time, the optimal condition of anodizing voltage was studied by increasing the anodizing time. The results clearly showed the nanoporous ATO over the films and the thickness of the nanoporous ATO is approximately 260 nm.

Modification of Structural and Vibrational Properties of ZnO Nanoparticles Prepared by Simple Chemical Precipitation Method

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.

Supercapacitive Properties of Cobalt Oxide Thin Films Prepared by Electrostatic Spray Deposition Technique at Different Substrate Temperature

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.

Effect of Annealing Temperature on Structural and Optical Properties of Cobalt Oxide Thin Films Prepared by Electrostatic Spray Deposition Technique

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.