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Tailoring the structural and optical properties of fabricated TiO2 thin films by O2 duty cycle in reactive gas-timing magnetron sputtering
(2023-08-01)
Chittinan, Donyawan
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Buranasiri, Prathan
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Lertvanithphol, Tossaporn
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Eiamchai, Pitak
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Tantiwanichapan, Khwanchai
Titanium dioxide (TiO<inf>2</inf>) thin films were deposited on silicon (100) and glass substrates via conventional reactive sputtering and reactive gas-timing (RGT) sputtering techniques. The duty cycle of supplied O<inf>2</inf> gas determined its effect on the properties of the TiO<inf>2</inf> films through spectroscopic ellipsometry (SE). With the best triple-layer model for SE fitting, the films' structure and optical properties were analyzed and compared. The high-resolution transmission electron microscope (HR-TEM) showed good agreement with the structure of the SE model, while the grazing-incidence X-ray diffraction (GIXRD) confirmed the crystallinity of the films. The results showed that the duty cycle was a crucial factor in the deposition rate and crystalline phase of the TiO<inf>2</inf> films. The optical reflectance (%R) spectra were measured by a UV-VIS-NIR spectrophotometer, representing anti-reflection properties at a specific wavelength related to the duty cycle. Moreover, the omnidirectional optical transmittance (Omni-T) profiles were also determined. The results showed that the transmittances (%T) of TiO<inf>2</inf> film near those specific wavelengths were enhanced over the bare glass substrate at a wide angle. In addition, photoelectron spectroscopy (PES) was used to confirm the chemical states and atomic compositions.
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Study on detection of carbaryl pesticides by using surface-enhance raman spectroscopy
(2020-01-01)
Chakaja, Chaiwat
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Limwichean, Saksorn
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Nuntawong, Noppadon
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Eiamchai, Pitak
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Kalasung, Sukon
In this research, the Ag nanorod structure was used as surface enhanced Raman scattering (SERS) chip which provides a sensitive detection signal for trace analysis of carbaryl pesticide. Carbaryl in solid form was measured by using the standard Raman spectroscopy to investigate the spectrum. Carbaryl at various concentrations was prepared in acetonitrile and dropped on the SERS chip for measuring Raman spectrum by a portable Raman spectrometer. The measurement condition including laser power and exposure time were studied to test the performance of SERS chip for carbaryl detection. From the results, the SERS chip useful for enhancing the Raman scattering signal which was increased depending on the laser power and exposure time. Carbaryl can be detected on SERS chip couple with the portable Raman spectrometer with the limit of detection of 10-5 M.
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Rapid detection of cypermethrin by using surface-enhanced raman scattering technique
(2020-01-01)
Leung, Wipawanee
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Limwichean, Saksorn
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Nuntawong, Noppadon
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Eiamchai, Pitak
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Kalasung, Sukon
Cypermethrin is a toxic pesticide in the pyrethroid group. A Surface Enhanced Raman Scattering (SERS) based sensor has been developed to achieve simple pesticide sensing. In this work, rapid detection of cypermethrin by using the handheld Raman spectroscopy coupled with SERS substrate was demonstrated. SERS-active silver nanorods substrate was used to enhance Raman signals of test samples. The effect of exposure time and drop volume of sample was studied for cypermethrin measurement. The results found that the silver nanorods substrate can be used to measure cypermethrin in the range of 10-6 to 10-3 M with a handheld Raman spectrometer. Furthermore, the Raman signal of cypermethrin was confirmed by measuring solid cypermethrin with the standard Raman spectrometer. SERS substrate was competent to detect cypermethrin with a limit of detection (LOD) of 10-6 M.
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Fabrication of zinc oxide nanorods for photoelectrochemical water splitting application
(2016-01-01)
Phetban, Poosuda
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Khemasiri, Narathon
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Kalasung, Sukol
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Jessadaluk, Sukukittaya
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Horprathum, Mati
Zinc oxide nanorods (ZnO-NRs) as a photoelectrochemical water splitting electrode have been fabricated by the seed-assisted hydrothermal process. Initially, ZnO-seed thin film was deposited on indium doped tin oxide (ITO) via DC magnetron sputtering system. Period to fabricate ZnO-NRs, the precursor concentration of zinc nitrate (Zn(NO<inf>3</inf>)<inf>2</inf>) and hexamethylenetetramine (HMTA) were precisely controlled during 10-50 mM, meanwhile the ratio was constantly kept at 1:1. The crystallography and surface morphology of the fabricated ZnO-NRs were investigated by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The XRD patterns perform wurtzite ZnO crystal structure of with the prefered orientation in (002) and (101) plane. According to FE-SEM photograph, growth rate, density and diameter of the fabricated ZnO-NRs electrode significantly increase, with the increasing of the precursor concentration. This precursor concentration provides a crucial role on the feature of ZnO-NRs for photoelectrochemical water splitting electrode. Finally, the photoelectrochemical water splitting performance was examined and provided that the precursor concentration became close to 30 mM in 1 M Na<inf>2</inf>SO<inf>4</inf> exhibited the highest photocurrent.
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Vertical alignment TiO2 nanotube based on Ti film prepared via anodization technique
(2016-01-01)
Aimpanakit, Kamon
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Jessadaluk, Sukittaya
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Tongmaha, Sunisa
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Supati, Attawit
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Khemasiri, Narathon
A highly ordered nanotube TiO<inf>2</inf> was successfully prepared from sputtered Ti metal film using anodization process. Ethylene glycol and ammonium fluoride was introduced as the electrolyte solution. The applied of anodizing voltage was systematically controlled between 20-60 volts along fabrication process, respectively. The physical characteristic of the fabricated TiO<inf>2</inf> nanotube including anodizing rate, tube diameter and tube width was investigated through the characterization system as field emission scanning electron microscope (FE-SEM). According to cross-section FE-SEM photograph, the anodizing rate and tube width significantly increases when the anodizing voltage was future increased due to higher the electric field. Moreover, the tube diameter directly depends with the anodizing voltage also. The anodizing voltage provides a significant role on the feature of TiO<inf>2</inf> nanotube. Finally, the fabricated nanotube TiO<inf>2</inf> is potentially promising for Photo-activated application and Nanostructure template.
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Effect of anodizing voltage on anodic titanium dioxide (ATO) growth based on an ethylene glycol solution containing NH4F
(2016-01-01)
Mangkornkarn, Chayangkoon
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Samransuksamer, Benjarong
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Horprathum, Mati
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Eiamchai, Pitak
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Eiad-Ua, Apiluck
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 (TiO<inf>2</inf>) 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 NH<inf>4</inf>F. 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.
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Crucial role of reactive pulse-gas on a sputtered Zn3N2 thin film formation
(2016-01-01)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Klamchuen, Annop
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Jessadaluk, Sukittaya
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Pankiew, Apirak
Herein, we demonstrate a powerful technique, known as reactive gas-timing (RGT) rf magnetron sputtering, to fabricate high quality Zn<inf>3</inf>N<inf>2</inf> thin films at room temperature without applying any additional energy sources. A single phase of Zn<inf>3</inf>N<inf>2</inf> film formation can only be obtained when a reactive pulse-gas of N<inf>2</inf> is utilized. We find that selecting a small atomic mass of sputtered reactive gas coupled with the pulse-gas technique is very crucial to adjust the number of sputtered atoms obtained from the target and enrich the forming energy of the sputtered Zn<inf>3</inf>N<inf>2</inf> films during the deposition process. Our results highlight that the RGT technique is a promising method to fabricate high quality sputtered compound thin films that can be applied in flexible devices. A simplified model of the materials system at the surface region of the de-nitride Zn<inf>3</inf>N<inf>2</inf> during ion bombardment is also presented.
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High performance metal surface coating using Ta2O5 thin film prepared by D. C. magnetron sputtering
(2014-01-01)
Khemasiri, Narathon
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Chananonnawathorn, Chanunthorn
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Horprathum, Mati
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Eiamchai, Pitak
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Chindaudom, Pongpan
Tantalum oxide (Ta<inf>2</inf>O<inf>5</inf>) thin films were deposited as the protective layers for the metal surface finishing by the DC reactive magnetron sputtering system. The effect of the Ta<inf>2</inf>O<inf>5</inf> film thickness, ranging from 25 nm to 200 nm, on the physical properties and the anti-corrosive performance were investigated. The grazing-incidence X-ray diffraction (GIXRD) and the atomic force microscopy (AFM) were used to examine the crystal structures and the surface topologies of the prepared films, respectively. The XRD results showed that the Ta<inf>2</inf>O<inf>5</inf> thin films were all amorphous. The AFM micrographs demonstrated the film morphology with quite smooth surface features. The surface roughness tended to be rough when the film thickness was increased. To examine the protective performance of the films, the poteniostat and galvanometer was utilized to examine the electrochemical activities with the 1M NaCl as the corrosive electrolyte. The results from the I-V polarization curves (Tafel slope) indicated that, with the Ta<inf>2</inf>O<inf>5</inf> thin film, the current density was significantly reduced by 3 orders of magnitude when compared with the blank sample. Such results were observed because of fully encapsulated surface of the samples were covered with the sputtered Ta<inf>2</inf>O<inf>5</inf> thin films. The study also showed that the Ta<inf>2</inf>O<inf>5</inf> thin film deposited at 50 nm yielded the most extreme protective performance. The Ta<inf>2</inf>O<inf>5</inf> thin films therefore could be optimized for the smallest film thickness for highly potential role in the protective performance of the metal surface finishing products. © (2014) Trans Tech Publications, Switzerland.
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Determination of thickness and optical properties of tantalum oxide thin films by spectroscopic ellipsometry
(2014-01-01)
Chananonnawathorn, Chanunthorn
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Khemasiri, Narathon
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Srichaiyaperk, Thanat
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Samransuksamer, Benjarong
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Horprathum, Mati
Tantalum oxide (Ta<inf>2</inf>O<inf>5</inf>) thin films were prepared, at different deposition time, by a DC reactive magnetron sputtering. During the deposition, a high-quality tantalum target was sputtered under argon and oxygen ambience on to silicon (100) and glass substrates. The prepared thin films were systematically characterized for both physical and optical properties based on spectroscopic ellipsometry (SE), and consequently confirmed by several methods. With the SE physical models, we could determine the thin film thickness as well as their inhomogeneity. The films thickness results were directly confirmed by field-emission scanning electron microscopy (FE-SEM) used to observe cross-sections, and surface profiler used to measure the physical thickness of the films. With the SE optical models, we applied both the Cauchy and Tauc-Lorentz dispersions in order to obtain the optical constants, to be directly compared with those from the Swanepoel method (SM). Our result showed that from the SE analyses, the SE physical model was obtained as the multi-layer configurations. The obtained Ta<inf>2</inf>O<inf>5</inf> thin film thickness was closely related with the measured result from the FE-SEM cross-sectional micrographs and the surface profiler. For the optical characteristic, the double layer physical model was best optimized with the Tauc Lorentz dispersion model for the most accurate results. In comparison, the SM technique also demonstrated a capability to determine both the film thickness and its refractive index only from some samples. Therefore, this study proved that the SE technique successfully and accurately determine both the physical and optical properties of the Ta<inf>2</inf>O<inf>5</inf> thin films. © (2014) Trans Tech Publications, Switzerland.

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